04-06-2019 22:22 - edited 04-06-2019 22:24
@Charleeif you are on a flex tariff you can drop down to a cheaper one but if not you are basically stuck with it unless you pay off your contract and start a new one. https://www.o2.co.uk/refresh/flexible-tariffs
OnePlus 6 (O2 & Sfr), Z3 Tablet (Three UK), iPhone 8+ (EE)
04-06-2019 22:23 - edited 04-06-2019 22:24
on 04-06-2019 22:25
You don't get billed for data unless you are outside the EU. Data would just stop once you reach your limit.
If your charges are higher each month it's very probable that these are charges outside your call allowance ie. calling numbers not covered.
Check in My O2 for any extra charges as you may also been scammed into an unwanted subscription.