I want CellC repair centre to take responsibility for the damage they have caused on my phone and give me a new or a phone that is working

I send my phone for repair to CellC repair centre to repair the screen as it was slightly cracked and the sim tray also was not reading sim1. I have insured the phone and the claim was rejected and I requested that my phone be bought back to me. When I send it, it was working just fine and now it is not working and there is more damage to it than when I send it for repair. The condition is worse than when I sent it and there are broken glasses in it. And there are brown stains in it. At the back it does not closed properly. The sim tray is very stiff it does not move smoothly. I sent it thru the store and collected it thru the store. Now CellC does not want to take responsibility for the more damage they have done on my phone and I am taken from pillar to post.