on 24-09-2023 17:35
on 24-09-2023 17:43
You can change once a month:
https://www.o2.co.uk/help/pay-as-you-go/big-bundles
If you want to opt out altogether, and so long as you have not set up to charge to a card automatically, and you have 0 balance, just stop using the SIM when the month is up. Note you will also lose the number, if you do not make a chargeable call at least once every 180days. Good luck.
on 24-09-2023 18:10
You can't opt out of bundles as that is all O2 offer.
To get basic old fashioned PAYG you need to change networks.
Look at giffgaff or 1pMobile