OUTSTANDING REFUND - TOTALLY BAD CUSOTMER SERVICE

I sent my product in for a repair. The Maintenance or Service Manager informed me that one of the parts had to be replaced. I confirmed in writing that I will pay for the replacement part, but they INSSITED I first pay for the part before they ordered it. Long story short, the replacement part did not work and the Manager committed to refund me. I am now waiting more than three weeks for my refund and nobody I providing me with a status update in terms of my refund. Totally bad bad service.