Battery Pro bellville burnt my car

I went to Battery Pro in Bellville Durban road to buy a battery. They offered to come out and replace the battery themselves. The guy came with me to my place to replace thw battery. Once we arrived at the car he removed the old and put in the old. Then a park like fire came out of the car only to find he had put the battery the wrong way around and burnt my terminals and other parts in the computer box. Now they wont take responsibility for the repairs.