It's probably only a tile mate but You'll need to call customer service. Numbers here Guide: Coronavirus Community Help and Support Advice from an O2 Guru regarding a way to get through: When it comes to the reason you are calling stay silent for 15 seconds and you will be taken to the keypad options. Press 2 for Everything Else Press 5 for More Options Press 7 for Anything Else which will put you though to someone. Say "Upgrade", "Lost/Stolen" or "Fraud" if you have to, to get put through to someone. 8.00am is the best time to call if you can.
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.