Engine brake won't turn off.

Truck in question is an '09 Freightliner Columbia.
The truck does fine in the low gears. Toggle switch in the off position. And i'm pretty sure it's the high setting that it's stuck on.
Wondering if anyone else had experienced this. I tried to explain it to the overnight shop guys but he want getting it. This is a temp truck until mine is fixed and he doesn't see this as an issue more as a minor annoyance

However, the issue is I can't shift gears with engine brake on. Especially with a heavy load. He'll even with a light load. And it's becoming dangerous.

Any advice would be greatly appreciated.

 

I'm checking the fuse box under the dash cover on the passenger side and I don't see a fuse marked engine brake. Did sound like a promising idea but doesn't seem to be a fuse in that location for it. I've also found there are 2 engine brake switch set ups. One is a single Toggle switch with HIGH Off LOW. The other set up is 2 switches. ON/OFF and HI/MED/LOW. I have the single switch set up if that makes a difference.

 

There is a problem with the system that I'm asking about.
The engine brake shouldn't engage when the switch is off no matter where my foot is.

 

I'm asking about fixing the truck, not adjusting my driving to compensate for a mechanical/electrical problem.