iMessage number different

I recently got a new iPhone and had my old number moved across. This is fine unless I am contacted with iMessage or use iMessage as it seems to still be on the new phone number and not my original. My original number comes up when I ring or message anyone not on Apple. I have gone onto settings and tried deactivating imessage and turning off for 10min and back on again as seen on some forums. But when I go to turn iMessage on the only options are still my new number and email. The new number is greyed out also and can not be unticked?! Please help!