Whose at fault? SPAR or Bobtail

Last week I bought bobtail dog food at SPAR Mathambo, when I got home I found out that the dog food had molded but they expiration date was for next year (2019). I then took the food back at the store at which I bought it from but I was told that it is not SPAR's fault that the food had molded it is bobtail. In my opinion SPAR could've taken responsibility because they are the distributor and I bought it from them.