Bad Services and inconsiderate of their customers

I took my car for a service on the 10th of February 2023. I had to pay cash as my service plan has expired. They charged me double the amount I was supposed to pay. I have been asking them to refund my money and to date they still tell me their bank is busy investigating and it's been over a month now. Every time I call them, I'm told the same story "we will follow up with the bank" or "the bank is still investigating" This is so frustrating!!!