E300 damaged from tow

[EdzBenz]

Fellas,
The SOV on my E300 failed a little while ago and I had my car towed to my mechanic. As the tow truck driver was "winching" my car up onto the flatbed, the metal coupling from the winch line caught my front bumper valance. This resulted in the metal coupling ripping out a big chunk of plastic from the valance. Nothing else was damaged.
I have some questions regarding this:
-Are tow truck drivers personally responsible? Or, do they have insurance to cover this? I'm asking because I sent the damage estimate to the tow company and the driver called me back explaining that he was personally responsible. He also asked me to have my vehicle repaired at their body shop instead of where I normally get my car fixed. I don't want to put a financial hurting on anyone so I agreed to let his guys fix the valance. Should I get the work they propose to do in writing prior to delivery?
-I was quoted a total of $595.17 from my own body shop to replace the front valance, color match the paint to the body of the car, and installation. Does that sound high?
I'd appreciate any comments or follow up questions that I should consider. Thanks,