Discovery debits me for 3 premiums in one month.

My bank account was double debited on 01/09/2019 as I had made a manual payment on 27/08 and Discovery had already processed the debit on 24/08. I was assured that the extra premium would be refunded. The turn around time for this is 7 working days. On 11/09/2019 they debited my account again for another premium. Now I have to wait another 7 working days for this to be refunded.