Misinformation about service plans

I bought my Ford vehicle in October 2016 with a 4 year 80 000km service plan. I wanted to take my vehicle for service on 60000km but was told that the 4 year service plan has expired in May 2020. I tried to speak to the dealership where I bought the vehicle but they simply indicated that they are sorry I was misinformed and that they will not be able to assist. Very poor after sales customer service.