Chevy with brake controller problem.

I have never had any problems with the standard brake lights not working. I am not sure what kind of testing they were doing. We were left walking around the dealership after closing looking for my truck. I left my cigs in the truck and needed one badly, so I started walking around looking for my truck, and found it with several people standing around it. When I walked up, I told them I needed my cigarettes, they started trying to explain why it wasn't ready yet. The guy that was trying to hook it up looked very frustrated, and proceeded to try to explain why they couldn't get it working. Basically telling me it was a factory wiring harness problem, and to take it to a dealer to get it looked at. This was Saturday night, and I don't know about you, but I don't know any dealerships that are opened on Sunday, much less the service department!
They are going to deliver my camper to me free of charge, but I need to get this issue taken care of before going camping. I looked on the Tekonsha website for help, but all they show are instructions for are 2007 classic body style. Nobody seems to have instructions for the 2007 new body style!!! Very frustrating!