Spend cap

[Josss89]

can u change my spend cap

[jonsie]

Only customer service can change the spend cap @Josss89 

It can't be done online

Guide: Spend caps on O2 

You'll need to call them.
All Numbers are here

Guide: Coronavirus Community Help and Support 
Or advice from an O2 Guru regarding a way to get through:
If you call 202 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.

Choose upgrades or even fraud options