Fungus Bun Steers

Today my friends went and purchased 3 wacky Wednesday burgers at Steers Queenstown their order number was 62 and to my suprise as i was about to dig into my second burger i noticed that the burger at the bottom had a greenish greyish spot which i later discovered was fungus. Who in their right state of kind doesn't check the expiry date of the food they serve their customers? I am livid and currently am 9 months pregnant should anything happen to my baby i am taking them to court