I have a policy with the unlimited for the past 9 years

I have a policy with the unlimited for the past 9 years .and the month of September 2023 they debited on the wrong date which caused me an interest with my bank ,when I query that thy refused to refund the interest I was charged die to their mistake. They acknowledge that it was a mistake for them to debit on a date we did not agree on but refuse to pay a charge I got due to their mistake. This really inconvenience me especially in this economy we leave in South Africa.