Hyundai Sonata 2007 2.4 auto

I had an accident whereby someone crashed into the rear of my car at a robot. After the car was repaired I complained about the auto gearbox making noises and sticking. A test drive was done and they found nothing wrong. The sound became worst and eventually the gearbos started slipping leaving me stranded in Gauteng ( I live is Stilfontein ). I had to make my own arrangements for transport and had huge expenses to get the gearbox repaired. When I approached Alexander Forbes they said they will get someone to investigate the damages and rep**** that they think it could have been due to either dirty oil or a low level of oil which caused it. I had the oil and level checked prior to the damages by two co's and was told it was fine. I still maintain the damage was due to the accident as the car was in drive when the accident occurred. I am stranded now because I have already spent R 20000 to get the car fixed and it is still not 100%. I need a car to do business, otherwise I will face bancrupcy.<br> Please help.