If the service was done at the dealer, any dealer can pull up the service records. You might also be able to get them from 800-FOR-MERC. It is possible they are trying to hide problems from you, it is worth checking. This is one of the advantages to buying from a private party: my car came with full service history, including the less flattering things that had been done (hood repainted due to serious scratches from a garden hose).