Sorry to read about the situation. I totally relate to your predicament- when I encounter mechanical, cosmetic,& aesthetic issues with my '94 E320 Starmark Coupe, it always incites a strong emotional reaction- never fails.
To best address these types of issues I first acknowledge my emotional state and then meticulously focus on a logical process/plan to gather complete information on the failure, causes, and solution-resources/options (as appropriate). Thereafter, I allow myself to make an educated decision on how to proceed to achieve the outcome desired.
I've learned that often my suspicions are just that, they do not foster a friendly trusting relationship with those that can help resolve my problem, and left running wild- impair my ability to make the best results happen. I am cautious though not to be too trusting and be placed in a situation to be taken advantage of.
Good luck with your information gathering, problem solving, and in making the best situation out of this unfortunate circumstance.
Keep in mind that MBZ's in general are very robust- however there's no real way to know for certain the effects of a previous owner (caveat emptor) and the randomness of chance circumstances.