GiffGaff mobile phone network

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I've been recommended GiffGaff, as they seem to have a good deal on unlimited calls + texts. Anybody with GiffGaff? What are they like? How easy is it to change mobile phone provider/unlock mobile phone to them? In looking on their website there seems lots of information, but how simple is it to sort it our yourself?
GiffGaff ?

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I think it was straightforward to change. I used GiffGaff for a short time. My only problem with it was that when I had a technical problem (at that time I wanted to speak my own voicemail introduction message and didn't realize it isn't common in this country) the only way to get support was through the community, that is, in a forum, and I got some stupid replies from people who had nothing better to do that to post useless replies online. I then went to Tesco Mobile, which I liked a lot, but there was an O2 bandwidth problem once so I went to Three, who seem OK but they sometimes offer me useless advantages designed for a younger age group.
If you are coming to the end of a phone contract i would ask your current service provider what SIM only deals they have?
My partner just finished with EE on contract and they did her a storming deal on SIM only. Much better package at less than half the cost of her contract.
GiffGaff are fine but the main service providers have caught up now.

When my phone contract ends next year I'm going back to a basic non smart phone and save a fortune.
These new smart phones they don't even feel like they are yours or that you have much control over them.