Farm inn food cause us to have running tummy

My colleagues and I had our end year function on Friday the 30th November 2018. We had their buffet for lunch. 90% of my colleagues had running tummy from 2 a.m that night, some their stomach ran the whole weekend and they only ate that budget that day. When we try to report this to farm inn we were told we are the only group that complained, we must wait for other groups to complain then they will investigate. This is not acceptable as they put our health in danger.