worst service from Mercedesbenz Sandown

I bought a Mercedesbenz a year ago as a second hand.. It had 49000KM on it. I was told that mercedesbenz will cover maintenance and service up untill my car is 100000KM or 5 years which ever comes first. when the car was on 98000KM i took it to Mercedesbenz for a service so that it can still be covered within the 1000KM I was old that the car cannot be serviced as the service dashboard is still showing that the car service will be due when the car is 102000KM . now after three months when I took the car in Im told I have to pay from my pocket because the car is over 100000KM. but I took it when it was 98000KM and i was told its not possible then. untill it was 102000KM. This shows that Mercedesbenz never wanted to do the 100000KM service. now my husband is stuck at work no communication from Mercedesbenz except that they did us a favour because the car was not booked in.