How to change mobile number in imessage & facetime so it shows my new number

Hi,

I have recently changed providers and had my old number ported across to the new provider which seems to be working ok with phone calls but not with imessage & facetime - both of these are showing the number provided by my new provider and not the one ported across from the older provider. How can I change this so that my original phone number shows - contacts etc. don't know its me that's messaging as the wrong number is showing.