Rotten meat

We bought a pack of T bone steaks on the 31st of December for a braai on the 1st of January, we took it on the 1st of January and the meat stank like it was rotten, the smell was unbearable, it was also slimy, we tried to return it at sandridge pick n pay we were told they can't exchange because we didn't have a slip, we didn't expect to keep a slip for meat that would become rotten an entire week before the expiry date, it is absolutely disgusting that they would rotten meat to their loyal customers especially considering all the diseases going around.