Cancellation gone wild!!!

I called to cancel my policy with iWyze but I was **** to and told I cannot cancel with immediate effect and that I needed to give a 30 days notice, I told them I got a better policy elsewhere and need my cover to be canceled on the 19th February 2023, and from the 20 Feb I will be with the newer insurance.

Now my cover is still active until the 09 of March which overlaps. I need the cancellation date to be on the 19th of February and the debit order from Iwyze must not go through because I will be debited twice.

The second time I called they said they can't assist me anymore because the cancellation is already processed. How is it my fault that the first person **** to me when I tried to cancel? PLEASE ASSIST ME WITH THIS, THE CANCELLATION DATE IS 19 FEB 2023.