If there are skilled folks around...why do things like this occur...
Years ago (before we had NAT,about 12yrs) I bought a gas range from a
large appliance dealer.
I had to buy a propane conversion kit (couldn't order it that way).
The dealer would not do the conversion, the gas company wouldn't
either (I assume they had liability issues).

I followed the directions, and assumed my own liability...I needed no
degree...it was straight-forward.

Trained people are under pressure...they sometimes make mistakes.
If you are patient, logical, and read the directions...you can make
many repairs yourself.