Disappointed costumer

I took my car to Midas in Alberton fir battery installation & everything was working very good on my car. After the battery was installed my car interior lights , indicators & electric windows are now suddenly not working I took the car back & reported that I have this issue after them installing they checked the told me that their battery is fine I have to my an electrician to check for me whats the issue because it's not their responsibility I took my car for diagnose that shows the commutation failure due to battery installation now I have to take out of my budget o lot of money Again to replace the junction box the guy who was helping was so rude said there is nothing he can do except give back my money & take their battery which there is no point because I still need to fix their damage I am very disappointed at how such a big company handles their customers...