I have recently changed from O2 to BT for my mobile supplier. I had my own iphone 5S and have now got a sim only deal. When swapping over I took my old O2 number with me. However my iphone is still showing my new BT number (which I technically no longer have) and when I text people it comes up with this number not my correct one. I've tried everything to get this to change on my iphone but can't seem to correct this. I've turned it off, removed SIM, signed in and out of itunes and I've run out of things to try. Any suggestions please? I'm not very technial so please keep it simple ha ha.