@Jodi1
How to top up here Guide How to Top Up (PAYG)
If you just want to change your tariff, you can do it in your MyO2 http://www.o2.co.uk/myo2
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)