Unwanted repair destroyed my PC

I took in a fully functional, smoothly running PC to the Bonaero Park branch to prove that the controller l bought from the store did not work on my PC. They kept my PC for the entire day to tell me exactly what l told them to start with & when l got home found that my resolution had been changed & that none of the USB ports worked. Thus was further inconvenienced by them having to keep my PC for a second day to repair the damage they had done & then they have the audacity to attempt to charge me for repairing the damage they did!