My experience with a TransGo kit was a disaster. The result was a trans overhaul. Their service policy seems to be "ignore him until he goes away. " Some people have done ok with a kit, but I suspect that their quality control is poor. That kit may be part of your problem. A good after market VB is not that expensive.
Your comments about what the dealer and trans shop makes me think you need to find someone else to do your work. There are a lot of mystery switches on 47RE transmissions without reports of problems like yours. There are controller boxes made for the 47RE so you can use your exhaust brake. DTT's Smart Controller is one of them. A controller box is not as flexible as a manual switch, but it will protect your trans from operator blunders.
It would be a good idea to fill out your signature so we would know about your truck to help you quicker.