Warrant/Service History for a Second hand Car

I bought a second hand car at Nissan McCarthy Randburg early this year 2018. When I bought the car it was a 45 000km on the clock a Ford Figo 2017 model. I was told the car was serviced for 40 000Km and its still on warranty as they say it was having a clean service record, when ever its due for service I must take it to a Ford Dealer for Services. When I got the service history Book, I noticed that the book was not stamped at all. I queried this with the sales lady and she say everything its fine she just need to take the book to be stamped. She took the book for some weeks after I had collected the car hoping that she was rectifying the service history book. I then got the service history book back but it was not stamped. I was not convinced when she told me that all is in order, I just have to take it to the dealer when ever my car is due for Service. Having not been convinced with this service history book, I went to a ford Dealer just to check if really what I was told about the car is correct pertaining the service history and warrant. To my surprise I was told that the car was never serviced for the 20 000km and hence the warranty had expired. What I could not understand is they say the car was serviced for 40 000km to one of the Ford garage, as it reflected in their system, but the book was not stamped. I contacted Nissan Randburg were I bought the car about the warrant and the service history, since when I bought the car I was told the car has a clean service history and is still on warranty which was not true since the was not serviced for the 20 000km. I was really disappointed and I feel cheated by Nissan McCarthy Randburg. From all this I was told that I must pay for the service myself because the car was no longer on warrant which is not what was communicated to be when buying and even after buying the car. Really I was cheated so as to buy the car from them by giving me false information.