Shocking service

The service offered by this dealership is nothing short of shocking. My car was there for 3 days and the only updates I got were when had to call to find out what was going on. After 3 days they had not repaired the car and was told they need to order parts and that would take 5 days. When I did get my car back after the second booking, the problem still exists. To make it worse, when I opened the bonnet a few days later, I found loose nuts sitting on the side of the engine bay. Even after informing the service advisor and sending pics of the nuts, not even acknowledged or responded to. Is my car safe to drive, who knows what those nuts are meant to secure????? Would highly recommend anyone to avoid this dealer and travel further to get better and more competent service. In fact it has put me off Mercedes and I will go back to BMW for my next vehicle!!