Social services not helping, I'm desperate

For issues specific to autism / Asperger Syndrome.
Just a quick bit about my situation. I am a 38 wife and mummy of 3 girls, 5,8 & 12. I have an autistic sister who is 16. Sadly our father passed away 6 years ago and then our dear mum suddenly died 3 days after Christmas 2016. My sister came to live with my family straight away. My sister has been a child in need for the past few years, my mother was disabled and struggled with losing my dad and also with coping with my sister) and so social services were involved to provide support to them.
In the past we have had my sister to provide respite and know that it is not possible to care for her long term. Social services were aware of this from day one that it was short term. My sister is sleeping on my sofa (she has hypermobility so this is not suitable). She can be very difficult, no boundaries, often talks and writes about inappropriate subjects including anal rape, murder and so on. My children are being greatly affected by all of this, constant crying. My sister also self harms a little, steals and lies constantly. There are too many things to list but the simply fact is I cannot have her with us anymore. I myself struggle with suicidal thoughts on a daily basis and can feel myself at breaking point. I have told ss this so many times but they aren't helping. For 6 mths they have ignored us all, no support at all. At the beginning they tried to get my sister to sign section 20 as it was 'easier for them', I refused as she does not have understanding and shouldnt sign if that is the case. So finally after 5 1/2 months ss found some supported living and she was going to move in on Monday just gone but we have now been told that it could be another 3 mths! Family rights group have advised me to take my sister down to the office with her bags but I don't want to put my sister through that, it would be very traumatic for her and me. First of all Ss told me they will not accommodate her but I know this is a lie as my sister is CIN. Then they told me if they did she would definately lose her supported living placement, another lie! Now they are ignoring my calls... What can I do other than take my sister to their office. Thanks for listening X by the way I have put a complaint in about ss about 8 weeks ago and heard nothing apart from 'it's on the desk'
Also can I ask if there is financial support I should have received? My sisters disability went over to pip and there has been a problem so that has stopped and so was my careers allowence, I only received a couple of payments in February. Ss said they would sort all of that out but haven't! Thanks X
What about your sisters education?

There may be a college which she could go to?

What about the team at your council which deals with children with special needs, contact them?

Contact your local county councillor
Try SNAP. Special needs Advisory agency
Trying to recall the technical name for your position?

Something like family member fostering?

Also try the CAB

Go into SS office and ask to see the Senior Duty Officer

Ask them to check what has gone wrong urgently. Has someone lost the file

Find out who your local councillor is and contact him or her urgently
Ask SS for a respite break

It sounds as though the file has been forgotten about
Make an urgent appointment with CAB

There are a number of issues here

Ask DWP if you can be Appointee for your sister. You need to ask were her PIP. Has been sent to. It may be in a bank account somewhere?
If you go to the local authority website you should be able to find the phone number for the Children's Department Complaints Officer, and also their email address. Write down everything you have said here, but also include her age. Head the letter "FORMAL COMPLAINT". That's really important. Then copy it to the Director of Social Services, the social worker who has been supposedly dealing with it, her team manager, and also your local county councillor and the head of the Children's Services Committee.
As your sister is disabled she should have had a Needs Assessment within the last year, and you a Carers Assessment. Were these done/updated? You should have a copy of each if they were.
If they haven't been done/updated, make a formal complaint about that too.
I have just been granted Legal Aid to fight our local council. As long as your sister doesn't have much in the way of savings, then she may also be eligible. Just Google Legal Aid plus the name of where you live and you should find the approved solicitors. Good luck, come back here for as much support as you need.
On the subject of finance, what are the LA giving you at the moment, if anything. Are you your sisters DWP appointee dealing with all the benefits? Has anyone told you she might be eligible for ESA?
Carers UK has a brilliant helpline, ring or email them and they will be able to discuss everything further with you, in confidence.
Thanks for all the advice, sadly things have become a lot worse since this morning. I called ss and spoke with manager, told her again about being at crisis point and about my mental health, she responded with' well we should be looking at your own children then'! I see that as a complete threat against my own family. It's so so upsetting that all I have done is to care for my sister and my family with no support and now when I threaten to drop my sister at their office they start on about my girls. Really not helping how I feel, I haven't done much with my life but pride myself on the job I have done with my babies, they are my world and beautiful, well mannered kind little girls. They haven't lost a file or anything they just ignore me or fob me off with lies. I have spoken with the local government ombundsman who have written a formal complaint on my behalf. I now feel forced to put my sister through the distress of being left at their office, especially now that they are bringing my children into it. Can they really start looking at my girls, I have nothing to hide but surely this is not fair.
Oh and no assessments have been done on me as a career, they haven't done any safeguarding checks or anything, I'm sure they are suppose to as my sister in a CIN. My sister is at a school for children with special needs but unfortunately they do not have any space for boarding at the moment.
La aren't giving us any money. My husband was made redundant as well so that's not helped, my sister received one lot of disability payment but nothing since, social worker told me it can take 16 weeks but not coming back with any other information, we currently have no income and just surviving on redundancy money which is fast running out.