DISGUSTING SERVICE

In January 2018, I purchased a Mercedes Benz ML400 from a dealership in Rustenburg who gave me good service. They sold me a service warranty for 140000km's for an amount of R56 259.00. Not once was I told that if the service is overdue I would forfeit my warranty which I had already paid for. I don't drive the vehicle often due to the high crime rate so when I did eventually drive it, I discovered that the service was overdue by 180 days which I would take responsibility for and gladly pay a fine. I call Mercedes Benz Constantia Kloof on the 18th July to explain to them what has occurred and the guy tells me that I have forfeited the service warranty and should buy a new one which would cost me R96 000.00. Surely they should work according to the mileage used since purchasing the vehicle. I purchased the vehicle at 53400 km's and it now sits on +- 63500 km's. Is this how they make their money by *********** the consumer? I would like to take this further as I am not prepared to lose R56259.00 without a fight.