Taking money that's not yours, is theft ADT

ADT was my security service provider. I cancelled their services in November 2021. To date, ADT keeps on debiting my account. I have tried every avenue to get ADT to refund my monies, but despite many promises to resolve this issue, no resolution has been forthcoming. Taking money that is not yours, and not returning it when you are made aware that it is not yours, is theft, ADT! Come on, you can do better than this. Refund me my money and stop taking unauthorised debit orders from my account.