Nissan Motordeal (Ormonde)

I booked my car for service with Nissan Motordeal (Ormonde) and i asked them to check if the car is still under service plan and they said i should just bring the car in today and they will check before they do anything, this morning i went there the lady that i got there also said she will check if the car is under service plan and get back to me ASAP. now they phoning me telling me the car is done and it doesn't have a service plan i will have to pay from my own pocket and i'm asking them how did they service the car without checking with me first if i will be able to pay for the car, the lady said they never check all they do is when the car is booked they just do the service. all of a sudden it is my fault and i should pay, i am very disappointed.