My daughter has had a similar experience with O2 recently.
She was rung a few weeks ago by O2 saying if she extended her contract she could have a new phone. She said there was a phone coming out soon she wanted, but nothing around now.
The O2 person insisted she take a new phone now and said he would send her one, which she said she did not want. He said he would send it anyay, and for her to refuse the delivery when it arrived.
We were out when it arrived so she rang O2 to complain and they said send it back.
O2 said it was an outside agency they had employed who had overstepped the mark.
We sent it back, but O2 said they never received it. My daughter spent ages on the phone to O2 and the Post office trying to sort it out.
After THREE WEEKS finally O2 admitted they had got the phone back, and they now plan to send out the new phone soon.
Use O2 at your peril.