Glass in our pizza

We went out on the 3rd of January to go and buy pizza from Romans pizza in wilkoppies klerksdorp. We got home and started eating. Halfway tgrough my wife's pizza se came across a piece of glass in het mouth from the slice of pizza she started eating... I phoned the manager and told him my scenario and he said that they dont work with glass. So where did it come from. He wanted to give me another pizza. But i don't want pizza from them anymore...