Unable to prove that they serviced my vehicle !

I drive a 2011 Volkswagen Polo 1.6 which I am buying over from my company, they deduct off my salary every month. The cambelt decided to give in after I only did 6000km on the car, it now stands at 148 000. The cambelt service was done in August 2013 on 90 000km by McCarthy Witbank, however there is no way it was done properly as the belt is worn away, cam pulley, tensoiner, water pump pulley, diesel pump pulley and the crank sprocket need to be replaced and I should have gotten another 90 000km out the car before the next replacement for which i would have saved !. R9813.00 to have fixed which I cannot afford on a Receptionist salary. Upon being asked to provide proof that this service was done properly, got told that they had a system upgrade and therefore are unable to provide proof, but they know for a fact it was done! (??) However by law you are required to keep your documentation for a minimum of five years! I am completely *****ed now, have told them to do the work on the car but have NO idea how I am going to pay for it. I think it is ridiculous and a load of nonsense that they cannot prove to me they did things properly, if it had been the car would be fine! <div><br></div><div><em>(Supplier name changed from Volkswagen to Mccarthy by hellopeter.com)</em></div>