Incompetence

I called Innovation Group on the 19th March 2018 because I wanted to take my car for service and they sent me a list of all the dealers nearest to me that I can chose from which I did and I am now having a problem because Hyundai doesn't want to pay for repairs because they say the dealer I took my car to is not Hyundai approved and that has tarnished the car warranty. The consultant I spoke to did not ask me if my car is still under warranty which I feel they are not highly qualified because that is the question they had to ask to make sure that all is in order. Their service is not excellent and they are not a good company to do business with. They should be liable for their incompetence and has to bear the consequences I am facing and also to make sure that I do not face this problem the next time I take my car to Hyundai by clearing the mess they have caused. Please help me!!