correct me if im wrong here, but if something is working before you take it to a mechanic, and its not when you get it back, it shouldnt be at my cost to repair?

i had to get the heater core replaced as it was leaking into the passengers side.. apparently a big job that requires basically the whole dash to be ripped out.

got it back yesterday and all the accessories in the dash are in different spots and now the mechanic tells me the fog light switch is broken and costs about $120 from seat... why should i have to pay for the replacement if it was working before i took it there?!?!?