Shocking way to run a business and they deserve everything they get.
Had similar, but less costly situation, myself recently.
My wife's mini convertible went in to a local garage a few units from mine for an aircon regas, the mechanic was reversing out but didn't see a car lift ramp that was at the same level as the rear screen!
Unfortunately the rear screen was broken and apparantly needed a brand new convertible roof, full respect to the garage because they arranged for a new to be fitted at their expense, no excuses. Got the aircon re-gas free and a full valet when we got it back
That is the customer service I expect if any damage is caused whilst in their possesion, the same customer service I offer!