Blocking debit orders from being reversed and Cancelled policy

I cancelled My Insurance Policy number ***, they still debited from My Bank Account when I Had to reverse the debit order from the bank. The bank said that the service provider blocked the debit order from being reversed. I have no credit arrangement with Auto & General and in that Sense I Do not owe them for them to block then debit order from being reversed. I called the service department they on friday the 22nd of November 2024 for them to reverse or Unblock the debit order so that I can Reverse it, I was requested a a bank statement and today is the 28 of November Still I have not yet being refunded. I have been with them for more than 4 years without even missing a payment.