Rosebank checker!

I bought food for lunch at checkers "Rosebank mall" the already packaged which was pap and checked, added with a potato salad aside only to find out the food is spoiled. How do you sell such to people? Even asked few peeps to taste on my behalf as I didn't want to conclude you bad as I've known you as a quality shop all the asked peeps experienced the same spoiled taste on the food. Had to spend my lunch without food. I made the complain but clearly it wasn't taken serious. If this is how customers get treated I'd rather take my service somewhere else. If you need pictures of that plate and sleep purchase I'll gladly attach.