Debit Order Blockers! Bad service!

I cancelled my contract on 01April2024. By phone call, I was told to send an email - eventually after 2 more calls and several emails, I got a reply 15 days later, also wonderfully mentioning that I will need to pay the next installment as it is 5 days prior to debit order date. I cannot stop the debit order as it is blocked!!!!! Quick to take your money, slow for any actual service! I refuse to pay for their delay! Contract cancellations comes from DEBT RECOVERIES - This isn't a debt recovery!!!!!