Poor Service ADT

I am writing to formally lodge a complaint regarding an incorrect debit order processed on my bank account after my contract with ADT had already been cancelled. Despite submitting a cancellation request and receiving confirmation that my contract was terminated, I was still debited thereafter. This constitutes an unauthorized debit, and I request the following actions to be taken with immediate effect: 1. Reversal of the incorrect debit that was processed after cancellation. 2. Written confirmation that my contract has been fully and correctly cancelled on your system. 3. Assurance that no further debit orders will be processed against my bank account. Kindly treat this matter as urgent and provide written confirmation once the refund and corrections have been completed. Also the manager PERCY was extremly unhelpful. He kept cutting the calls etc and never to reply yet i had addressed these issues. i had cancelled the contcat and given notice now the account is in arreas and affecting my credit