Very poor service

I had bought a Volkswagen Polo 1.0Tsi from Avis Bloemfontein. I had bought an extra service and warranty plan from them on the vehicle. I was told that the service plan was for up to 90,000km. No documentation was given to me, as the saleslady said everything is on the Volkswagen system. Now at my 45,000km service, I was informed by the dealer that my service plan is over now. I contacted Mr Wynand Rademeyer several times via e mail, with no response from him. I asked the sales lady also while ago, and she said that plan was for 90,000km. I am requesting from them to give me the necessary documentation of the plan that was sold to me for the amount I had paid extra.