Service plan

I bought a brand new car at Hyundai bedfordview in 2018 March the sales person told me that I must bring it for 1st when it reaches 30k...its been two years now and its still at 20k I called and asked them if I can bring it for service because it's been 2 years without the car being serviced and it's still on 20k they tell me that I have to pay because my service plan has expired..... They are so rude they don't even to listen to my side of a story they are telling me that they were not there when I bought it and I have to pay