Checkers Hyper Galleria selling spoilt lamb meat on special

I bought a whole lamb from Checkers hyper Galleria ,on Sunday morning. As usual I came home and thereafter I put it in the freezer, as I stay five minutes away from Galleria. Today my wife opened up the meat to marinate the meat for a braai that we are having tomorrow evening, she noticed it was spoilt from the smell of it.I called into the store today. I was put through to the store manager, but he refused to pick up the call. I spent alot of money on the meat and I do not expect to buy spoilt, rotten meat even if it was on special. I want it to be replaced with a fresh one.