Almost all providers require 30 days' notice if you wish to leave.
Contact the business and say you want to cancel the contract because you're still in the cooling-off period. You'll probably need to give them details such as your account reference number - check any documents or emails you have from the company.
Go to your O2 account and select 'Membership and Subscriptions' Scroll down to 'Cancel Subscription'
O2 end of contract tariff options If you happen to be out of contract with O2 already, it will send you an annual reminder that you're still paying for an old tariff. In these notifications, O2 will offer you a selection of new plans that you could move onto once your fixed-term is finished.
Simply sign in to My O2 and choose the tariff you want to move to. If you move to a lower tariff, you could lose some of your benefits – even if you move back to a higher tariff later.
O2 end of contract tariff options If you happen to be out of contract with O2 already, it will send you an annual reminder that you're still paying for an old tariff. In these notifications, O2 will offer you a selection of new plans that you could move onto once your fixed-term is finished.