Many times sleazy dealerships will intentionally mislead customers because they make more money from customer paid repairs than they do reimbursed repairs. Most car makers have flat rate labor that they are willing to pay and part of the dealership franchising includes a substantial discount for parts and labor.

You can test if your dealing with a sleazy dealer by calling up and asking for a next day appointment on some oddball warranty covered item on your car. Call back in 5 minutes and ask to schedule an oil change or major service next day and amazingly they are not booked solid for a week like they were 5 minutes previoiusly. Thats one of the reasons I never make appointments at dealerships. I show un announced and mysteriously they have always been able to get me a loaner and get my car in at the last minute if I was having a service of some kind done. One of the many tricks I learned from owning new Volvo's.

Call MBUSA customer service and find out if your car is covered or not. Report to them that their dealership is giving misinformation if it is covered (they probably won't care but you never know).