Just give customer service a call to swap your account and they will send you out a new sim with your number on it. Guide: How to find help & contact O2
I have no affiliation whatsoever with O2 or any subsidiary companies. Comments posted are entirely of my own opinion. This is not Customer Service so we are unable to help with account specific issues.
Currently using: Pixel 7a (O2 & Lyca), One Plus 6 (Sfr), iPhone 12 Pro Max (Vodafone)
Hey @Salisa19 , there's helpful info above from @MI5 so hopefully you got everything sorted with your account! Don't hesitate to come back and let us know though if you have any additional questions.