Cancelled policy

On the 28 of July 2021 I cancelled my policy with Miway before the debit date which was 6th August 2021 and they still debited on that day. I emailed to ask why they debited a d I was asked to send my bank statement which I did and now the response I got is that they cannot refund me as the premium stated from 5th of August endi G 6th September.

How is my premium starting on the 5th when I cancelled it before that date.