Unsuccessful 3rd Party Claim

In May of this year I was hit from behind by a client of Outsurance. Their client told me that he was not going to claim for his vehicle as there was no point because his damage was not worth the huge excess he was going to have to pay, we agreed that he would put through a third party claim. We both reported this to the police. He submitted a claim to Outsurance and the sent him a claim number, great start... I was extremely busy at work and not able to complete the huge number of requirement one needs for the claim, namely, pictures of just about everything on the car, a letter from my insurance, stating that I would not be claiming from them, my original registration papers to prove ownership, which I had to get from the bank, as it is on HP, etc. It came close to 30 days and I contacted Outsurance in a panic, as I know one has to claim within 30 days, however, I was informed by the gentleman on the phone that I had 3 years to claim. This was perfect, I was still swimming with work and this made a huge difference. A further 3 months went by, I was now able to take the time to get all this together, including a quote from a panel beater, which I had none previously, but it was only valid for 7 days. Once I had all this info, I contacted the claims department, sent all of this through with reference to the claim number, 2 days later I received a rather disturbing phone call from a lady informing me that Outsurance will not be paying out for the claim, by looking at the pictures they maintain that there was previous damage to the rear of my bakkie and they also don't know what happened since the accident and when I finally managed to put the claim through. I also received a snotty email saying that there were previous dents and scratches, therefore they are not held liable and will proceed to close my file. Do you mean to tell me, if there was a small dent on my tailgate, somebody smashes into it and dents it that its deformed and barely latches closed, that now they are not liable. My rear bumper both on the left and the right have dents on them, from other vehicles from knocking into them, however, there was no damage to the body of bakkie. I have full comprehensive insurance of my own, I told them to contact them and ask if I have made any claims on my vehicle, no, and I was not about to put a claim through and pay a R3500 excess which is claimed back by the legal department, as it was not my fault. Imagine I did that, I would never have got my money back if they base their claims on that principle. I am extremely unhappy with the ********* way that this is being dealt with.