I have had a really bad experience. Got an offer on line to buy my phone. Firstly, they didn't send me the return envelope as requested, they then did but when I sent the phone they said they hadn't received it. They then said they had got it so I would get a response in 48 hours- obviously I didn't! I eventually got a revised offer which was basically a joke- they said the phone was faulty but it isn't! I've asked for a revised offer or my phone back- not expecting a speedy response!! My daughter sold hers on Music Magpie and said how easy it was. I'm disgusting with Giffgaff.