Airbnb Refused To Refund Amount Paid By Mistake

I have booked from Australia an accommodation for 3 months in Cannes, France. As per payment schedule I paid some months ago the first instalment. As the credit card to pay further instalments will not be valid anymore for payments next year I tried to change to another card. Although the next payment is scheduled for 06/06/2024! my credit card was debited immediately. I must have talked to at least 20 different staff, all being very apologetic, but none of them having the slightest intention to refund the payment made in error over 9 months before payment is due. It is apparent that Airbnb is trying everything not to refund the amount received by mistake. I find Airbnb very uncooperative and not to be trusted. H. Nath