Poor services rotten food

I purchased two burgers at wimpy MALL@CARNIVAL collecting my food to my surprise when I opened it the one burger bun had molds on it and when I take it back the lady assisting just looked at me and said "oooh" took and said6i will make u another one,. No apology, No explanation, No remorse whatsoever. I then ask for my money back nothing was said to me she took the food and that was it. I'm a loyal customer at the brunch and never ever had such poor service in my life didn't expect such a performance from a Manager. Thought for eating such a disgusting burger and the after effect of it upset my all day.. I will never ever purchase there again and will make sure every one the mall knows about it. Food should be clean restaurants must be clean...?????