Debit order dispute

I cancelled my contract with cartrack and was told its marked for effective cancellation date is 2024/12/05 as there is a 20 working days’ notice period. No where was i told that i would be debited again this month, for a car that is not in my possession any longer. They taking a full moth premium, for a contract that will be fully cancelled in 6 days, this is *****. I want my money back