on 24-06-2024 06:19
on 24-06-2024 06:56
If you also cannot login to your MyO2 using a browser and this link, @DelBertie - https://accounts.o2.co.uk/signin
then you need to contact O2, all the ways are in Guide: How to find help & contact O2 .
If the web access works, as the MyO2 app can be a bit fussy, then remove the app, reboot the phone and reinstall the MyO2 app from your phone's app store. Good luck either way.