Does anyone here work in a restaurant, i have a question?

Does anyone here work in a restaurant? I have a question and maybe you can give some suggestions.

The issue is the takeaway people at the restaurant I work at have issues at least twice a night where they leave out important things like bread,butter, and salad dressings.

what is supposed to happen but doesn't obviously is the person bagging the order checks the order before they bring the order to front and the person that runs the order to customer checks it before they give it to them.

any suggestions for fixing this issue or any incentive Ideas for not leaving things out for a given time period

Yeah, write them up and then fire them if they still can't get it right. Simple