Service Plan

I bought a A180 in 2013. I took out a service plan to 100000km. I was not explained that I had to take my car for a service at 99 999 km in order for Mercedes to pay my service. I made the booking on 100000 now they refuse to pay as they say as soon as the car is on 100000 the warranty expires. I feel that this is unfair as I have paid for the service plan. Normally you can take your car 1500 before or after 1500 when the service is due. I don't know what is the difference on 100000 km. I have phoned the customer service and lodge my complain as I feel that they must still honour the service. I spoke to Themba and he said that a Manager will contact me. I phoned again and he was on lunch. I left a message and was promised that he will contact me and I am still waiting. I then lodge a complaint on the Mercedes South Africa email and they did not respond. How many customers are being ******* like this and then you must pay the service out of your pocket. Please I need assistance.