Renault Centurion

I lost my Service plan because of Renault Centurion I did take my car the 1st time at 1000km they bumped my car yesterday it was a small mark when customer service contacted me I told them I wasn't happy. The next time I did take my car I was told that I don't have a service plan. Customer service did contact me and I expressed my unhappy experience and even told them that the sales person told me it's included of a service plan. Yes it's my fault as I was supposed to know my contract. I waited en contact Midrand Renault where I did buy my car. I was told no I do have the plan. I told me they will call me for the appointment. I did take my car in and now I did loss my service plan because of Renault Centurion. I even complained and put a review. Know I'm losing out o and when I called Renault Centurion I was told they updated there system and they have no records of my car. How do I proof I wasn't totally in the wrong