@Pj4 O2 aren't very much interested in talking to customers these days unless they're buying something or upgrading. If you want to discuss your issue with customer service, below is the advice from an O2 Guru on how to get through.
Call 202 from your mobile.
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.
Other available numbers are here: Guide: Coronavirus Community Help and Support You have to lie and use the Lost/Stolen or Fraud options to get through. Otherwise you'll be disconnected. Sorry that sounds so pitiful, but that's the way O2 treats their customers.
Edit: If you have O2 insurance, see this: https://www.o2.co.uk/help/digital-services/o2-insurance
Track usage, upgrade and get support with the My O2 appDownload My O2