Saying the fitted a gearbox when they did not

I was involved in an accident in 2012 and my vehicle was insured by Absa insurance at the time,i submitted a claim and they sent Andre Steyn to assess the damage on my vehicle,after that my claim was approved and my car was taken to Auto 911 bodyworks in East London,whilst my vehicle was still there i met Andre Steyn in Butterworth when he went to assess my colleague's car and i asked about the progress on my one because it had been there for about 6 months then,he said they still have to fit a new gearbox on that car because that one was damaged by some shaft during the accident.i said ok because i also did not want a half done job in my car.Finally the guys phoned me and said my car is ready i went and fetched it and it overheated the next day on my way to Mtata and whilst i was looking for a second hand engine i said to Andre that the gearbox in that car is giving me problems,actually i am struggling engaging gears and i think the gearbox was not changed he said it was changed,i went back to Mayfair and they said they never fitted a new gearbox in that car and they never invoiced absa insurance or auto 911 for a new gearbox and they sent me proof(invoice),now he's not responding