Maytag gas cooktop too much flame

Question

I have a Maytag MGC5536 cooktop.  We use propane, and the Maytag dealer came and updated the orifices to the propane type after installation.  Problem:  Can't get the gas low enough.  Even on lo setting, there is too much heat--even on the back center (lowest burner).  Things burn in pots, etc.  The highend doesn't seem too high howeve, jsut the low end not low enough.(Is it as simple as replacing the orifices?  Too what?  Do I call the Maytag guy, or is it a home repair?)  Thank you for any insight on this.Bruce