I doubt if you can hold the shop liable for the damage.
Brake fluid is a common paint remover(acid) in the modelling industry, it is VERY powerful and you need to be VERY careful using it(gloves, etc).
If you soak ANY kit in it over a period of time it will result in a nice deformed/warped item, I usually use it on die-cast figures rather than any plastic ones.
Some of my WH 40K space marines got turned into Chaos marines after soaking them in Brake-fluid.
The strength of the brake-fluid varies from place to place in some you can use it straight i other you will need to dillute it. or use a soaked rag and wie the paint off.
Best option for you is to buy a replacement body if available and work from there.
If the Car is an off-the shelf ready to go Car than you are out of luck, if it s a Tamiya, Kyosho or similar simply buy a spare body and some new screws.