Denied service due to policy that is not written

I purchased a inner and outer CV joints for an Uno Mia 1.1 2001 Model at Autozone Kempton Park. Mr Jacob from there sold me the parts and assured me they were the right parts. The parts were bought and after some time fixed the car. the mechanic found out that the inner CV's were wrong ones. this was during the December break and I called the shop since I was more than 700 kilos away asking whether I can return them for a refund when I get back to Gauteng. I was told that they can be returned. I went there on the 12th of February after the long break I was in since December. I went to Kempton Park, with the CV's in their original packaging and with some oil stains on the outside (mechanic tendencies). The security guy checked them, got another guy to check them, who ruined the packaging by opening it roughly, and the goods were taken to the manager (security said so). then I was taken to Jacob who said manager says they cannot be returned. they have a 7 day return policy which is not on the slip that I produced to them. I was also denied speaking to manager when I asked to see him..