The new user needs to obtain their own contract (pass credit checks etc). Once they have their own contract, you can transfer your current number to it. Each account is then responsible for their own bills.
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)