I have done these dining hall shops in the past and never had an issue. I'm not discounting or minimizing your issues. As for deciding whether to continue doing assignments for Confero, that is your right as an independent contractor.
Arguing with fools is like playing chess with a pigeon...
...No matter how good you are, the pigeon will s@^t on the board and strut around like it won anyway.
Not scheduling for ANY company.