You said the manufactur said "It's on the stove"
You said "The previous owner had the 3 burner stove removed and a 4 burner stove installed"
So there you have it, the wires are somewhere under the range top, more than likely if you do not have a vent hood
On my coach the stove vent fan is in the hood but you have a different type of vent
You will need to pop the top on the range, if you have wires there you are good. if not then you will need a cable tracker (you can get one from Harbor Frieight, cable tracker is the key word)
And track 'em down.. When you find 'em you may find a switch, likely not labeled, or you may need to add one.
Home is where I park it!