It's 20gb of data included in the price you pay for the tariff. Your T&C's clearly state that you will be charged for going over and the bills are huge as I said they would be.
I'm afraid you'll have to pay for what you used unless you can find a sympathetic adviser to offer you a goodwill gesture.
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)