I received a copy of my venue's contract for my Dad to review before putting down a deposit. It has all of the standard legal type jargon about cancelling, vendors needing insurance, yada yada... but nothing about what is actually included in the service. Nothing about the cake being include, uplighting, linens, etc.
Did your contracts include this? If not did you find a way to incorporate? I started drafting my own "amendment to the contract" but I don't want them to laugh in my face!