Just a general comment to add to the previous posters.
I beleive with most organisations, Social Services, Education etc you are required to go through their internal complaints procedure first to see if the problem can be rectified/addressed before you go to an independent source. It is difficult, especially if the relationship with them has broken down, but it is the best way to do it.
More often than not, if you try and lodge an independent complaint, they will tell you to go through the internal procedure first to ensure that there is a possibility to put things right.
I lodged a complaint within Social Services about a Social Worker, she was removed from our case (which was a laugh as she did s*d all-hence the complaint!), we were given a different SW and a written apology. I'm not absolutely convinced they replaced her because it was the right thing to do but more so because they wanted me off their back.
Best thing I can suggest is get it all in writing. I was able to make my complaint via email, which was very useful as I had copies of all the emails I had sent to the SW and her responses to me, or rather the lack of them.
I really would encourage anyone else to do the same, if you are dealing with a SW, get their email address, also that of their line manager, always include a cc to the boss in any correspondence. If you don't know who the line manager is just ask, this info has to be given to you.
It is much easier to keep a track of emails than of letters sent via snail mail which they can deny getting, same goes for phone calls where it is all too easy for the truth to be twisted.
Easy for the guilty party to say "Oh but I didn't say that.." It is also easier for you as you can keep any started correspondence in drafts and come back to finish it when you are ready, I had to do this as my caree hardly gave me a minutes peace!
Last bit of advice, before you make your complaint, decide what you want. Is it an apology, a new worker, new line manager, you will need to be clear what you want them to do to put things right for you.
It sounds daunting but it doesn't have to be. Lots of luck