I've had a similar problem, and I am being told mine is terminal.
I've moved back to Virgin after a few years over on the dark side with Sky.
When I signed up I am 100% certain that I asked for my number to be kept, but Friday was my last day under contract with Sky, and the number didn't port.
I've been in touch with Virgin who say they have no record of me asking for my number to be ported talk to Sky, then Sky who say nothing we can do, number has been released back to Openreach, but try talking to Virgin Provisioning team.
Called back Virgin, and told there is no such thing as provisioning team, and I can't escalate call as supervisor is busy.
Not sure where to turn to next. I can't prove that this is a Virgin mistake, as they never sent me a "here is what you told us response" when I placed my order, but feel so sick of this at the moment. It just doesn't seem right that 1 business day after account closure the number is irretrievably lost, but I cant get hold of anyone in either company who is able to help it seems.
If anyone has any ideas where I can turn to next please let me know. I guess I can complain to Ofcom, but not sure whether that is the best next step, or if it will even help?