Dada Motors appalling service!

I purchased a vehicle from Dada Motors Potchefstroom under Inspectacar in April then I was advised that my car is still under warranty until I reach 60000km however last week Friday when I booked the car in for service I was told by Hyundai that the vehicle is no longer under warranty as the new IB models are only covered till 30000km. When I called Dada Motors they claimed that they didn't know that the car is no longer under warranty. I don't understand how they sell cars if they don't have full knowledge of the car models and how the warranty works. I believe as a customer I was supposed to be advised that the car I'm purchasing is out of warranty and that I should get a warranty/service plan . I spoke to one of the managers at Dada Motors named Shizat who had a very bad attitude and refused to pay the invoice for my car service because they were in the wrong for not informing me about the warranty terms. My car is stuck at Huyndai as the invoice needs to be paid and the dealership is refusing to pay.