Waiting 6 weeks (so far) for ******** debit to be reversed

I paid the final instalment on my account 28/09/20 and then was promptly debited for that amount as well. My account is now in a positive. I have been phoning and emailing since then to be refunded and am completely ignored. Furthermore your agents blatantly lie, pretending to be each other's team leaders so that complaints cannot be escalated internally. You should be ashamed of such ********* and ******* behaviour. Kindly get your house in order and refund my money at once.