Rotten service - only good at harassment

In October 2020 I settled a Jet account that was handed over to mbd and was advised I had paid an extra amount of R500 which needed to be refunded. I contacted mbd and requested they update credit bereau (still today they have not) and provide me with paid up letter (which I received after second request). I also requested they refund the extra payment made in error and I even submitted the proof of payment and banking details for refund and they have since ignored multiple requests to please refund. I contacted jet and was told there was nothing they could do as mbd was handling the finances for my case. I called mbd and they pick up and hang up not sure if their lines are faulty or if it's deliberate. They used to call over 3 times a day and text to harass me for payment before my account was settled and now that I have settled and require my refund they are suddenly no longer available. Can mbd please just do right for once. Update my credit record and refund my money. You're behaving like ******. Selfish and inconsiderate.