Spur burgers

I bought a pack of 4 spur burgers from checkers last Tuesday. They have been in the freezer. Today when I fried the burgers they appeared to be seriously off. The stench from the frying burgers was totally nauseating, needless to say completely inedible. very disappointing considering that the burgers are not necessarily cheap. I have two unfried burgers which I would actually like to return for either spur or checkers to test. Disgusted