Mayfair gearbox

My bakkies diff broke. It was sent to mayfair gearbox. I paid R22 000 and recieved my bakkie back. 5 days later it broke AGAIN. It was at this point where I realized that there was a different diff than my original in my bakkie. It was collected and a few days later I was told by a gentlemen named Deon that the sideshaft was broken and that I would have to pay R3600 for it to be repaired UNDER WARRANTY! They refused to cover the costs under warranty as apparently from Deons point of view it was due to hard acceleration and it was my fault. I asked them where my original diff was and was told that it was repaired and sold. My question is why was it not repaired and put back in my bakkie? I was forced to pay the R3600 before they would deliver my bakkie and told by Deon that I was only being charged for the parts and not for labour. This I found to have been a lie as when I recieved my bakkie and the invoice I saw that I had in fact been charged for labour. After this terrible experience I drove my bakkie with absolute care to not ever practice "hard acceleration" as they put it. But alas a week ago the sideshaft broke again. A lady by the name of Claudia booked it to be collected on the thursday. It was not collected. I called her friday and was told she was sorry she booked it but never followed up. It was collected on friday. I have been trying since monday to speak to someone to see what they are going to do to fix this situation. I have been promised a million times to be contacted by some sort of manager to no avail. Nobody takes any responsibility at this company. I am now suffering a great loss of income because it is my work vehicle. Legal action will ensue if I continue to get zero feedback and have to incur any further costs.