Poor service

I purchased a vehicle (BMW X1) from hyundai waltevreden. Before i took delivery of the vehicle i was promised a spare key from the previous owner. I went back a few weeks after to follow up on the spare key... i was told that the previous owner cant find the spare key but they will will make a plan for one. They admitted that its their fault that they should have taken off the money from the trade in from the previous owner to replace the spare key. i bought the vehicle in September and i had to be the one to contact Hyundai for follow ups. today 01/12/2015 i called and was told that there is nothing they can do for me because the BMW key is too expensive for them to replace and they will be running at a loss if they get a spare key made for me.... i don't think that its fair that i now have to spend money from my pocket to get a spare key made. i paid cash for the vehicle, they should have given me a discount for the value of the key.This is terrible service and unprofessional. They should in actual fact take the car back and i get refunded back my money as i purchased an incomplete purchase.