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.
Canceling a Cellular Service Plan To get out of a phone service contract, contact your plan's customer service. You can also try to sell your plan, contact a different carrier for help, or view your contract for loopholes.
Almost all providers require 30 days' notice if you wish to leave.
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.
Re: Keeping the phone after contract is done If you make all 24 payments then the phone is yours to keep.
When your O2 contract is coming to an end, the network operator will get in touch with you via text or email. 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.
Go to your O2 account and select 'Membership and Subscriptions' Scroll down to 'Cancel Subscription'