Rotten Chicken

I bought 5 piece chicken tray at Shoprite, Port Elizabeth, Pier 14, close to my workplace yesterday (04/02/2016). Expiry date is Sunday the 07/02/2016. I left it at home to be prepared for tonight. My sister just called that it changed color in the fridge & when she cooked it, it was smelly & became grey. Unfortunately I cannot return it to Shoprite because I stay far from where I bought it & cant bring it either tomorrow because I'll only be in the office again on Monday & cant keep it in my house that long as proof. I am so frutrated because I was looking forward to a nice chicken salad & it was my last cent. My Sister sent me a picture of the wrap with the expiry date on it.