Mix telematrix refuses to cancel my policy.

I had cancelled the policy in december 2023. They responded on 29 January 2024 that the policy will be cancelled on the 29th of february 2024. They did not dislodge the debit order and they sent a message that the account was in arrears, although it was paid by debit order, I made a manual payment but still they did not cancel the policy, instead they continued to request policy premiums.