Just changing tariff doesn't start a new contract. Your current contract still remains for the same amount of time it's just your included allowances that will change from the next billing period.
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.
Please select the post that helped you best and mark as the solution. This helps other members in resolving their issues faster. Thank you.