GMC A/C Control module Problem?

We have 2003 GMC pickup. The a/c started to just blow hot air. Our son reached up behind the controls on the dash, jiggled some wires apparently, and it started working. After we took a trip to Colorado towing our Fifth wheel, it started blowing hot again and we smelled wires getting hot. Took it into a Chev. dealer in CO. This is what they show on the repair invoice:

Found the HVAC control module had an internal short to ground blowing the HVAC Fuse. Replaced HVAC control module then the blower would only blow on the high setting. Tested the blower motor resistor. It tested faulty, so replaced.

Their fix: Misc diagnose & replace control head and resistor $127.50 Control $216.67 Fuse Kit $3.60 Resistor $55.52

We questioned why they replaced the high priced item first (complete control module) before they tried the less expensive repair. We were given the usual was-was response that made no sense. We were also told that this is a common problem with a GM component shorting out the module. What is your assessment? Maybe GM should have fixed the problem if it kept occuring? We think we were taken advantage of because we were traveling. But maybe not.

Thanks, Burl