Unfairly treated as a customer

I bought a bread from one of the local shops, we buttered the bread and my daughter eat 2 slices from it and when I was about to also eat the same bread my first bite I found a piece of ceramic bottle then I checked the next Alice it had the other ceramic bottle

The following day I wrote an email to blue ribbon customer care notifying them with this query, then they contacted me and ask me to give them details of my query , then they came collectected the bread of which they have tested and according to them they found a foreign wax on the bread and they apologized and offered a voucher of 40 for their acknowledgement. Further more there's nothing they can do about that I can even come to have a tour in their bakery to see how they do things

This is so unfair you do testing and find an object on your bread that made a child to get sick and cough blood all you can say is to come back and say that's a foreign wax . My question is that who baked their bread with foreign wax that makes us sick, we buy bread daily for them to bake it for us with foreign wax and it should be fine and offered. R40 voucher for that.