Stuck with temp number for imessage

I changed from EE to GiffGaff, with original number 123, and giffgaff temporary number 456. I gave them my PAC code, and the number was changed over to 123 (giffgaff sent an email to confirm transition). But when i put the sim card into my iphone 6s, the primary number coming up on my apple id is 456 - the temp number no longer in service. I can send/receive calls and texts on 123, and not 456. I added the 123 original number to my apple id BUT imessage and facetime will only use 456. I have turned off imessage and facetime, removed the 456 number from apple id and turned the phone off/on. but when i turn imessage/facetime back on, the 456 takes over, when i need the 123 number! HELP!