Rotten bread is my fault

We have recently changed to Spar because we thought there quality is better. Surprise! We came home with our on the 23rd of June and the next day opened the bread (we bought 2) and it smelled very funny. We tried it, it tasted horrible! Rotten! I did not even try the other bread. I closed the packaging and put it in the freezer. No get this: I am not going to drive back in the week between shopping as I work late and will not inconvenience myself for others mistakes. I went back on the 30 June when I do my weekly shopping. My husband gave them the bread and said we want to get our money back. She had the cheek to tell us the bread expired and why did we not bring it back sooner! It was not expired when we first opened it and it was already rotten! Again I will not waste my time and petrol to return food that should not be rotten in the first place! So she said we can take other bread and at check out she will deduct the 2 rotten bread. That is what we thought she did. When I got home - surprise again!- only one bread was deducted, when I gave back BOTH. So just tell me should I have driven back AGAIN? And now I do not even have the slip anymore because she took it! Just tell me- should I open every product in the store and taste it before buying, because whoever are suppose to check if food is not rotten was sleeping on the job it seems.