Both Suburban and Atwood water heaters have 'factory preset' normal t-stat and high temp t-stat
Suburban.....
Normal t-stat set for 130F & High t-stat (ECO) set for 170*F or 180*F depending on model
Atwood.....
Normal t-stat set for 140*F and High t-stat (ECO) set fr 180*F
Pilot flame water heaters do have an adjustable temp control lever...usually 110*F to 150*F.
Which Brand & Model do you have?
Suburban SW6DE, SW10DE etc.
Atwood GC6A-8E, GC10A-8E etc.
Brand/Model number listed on data sheet in outside compartment....should be on trailer data sheet also
And if the Western RV Tech/Service Department didn't know/understand how your water heater functioned..........:S
I'd find another place for service. Water heater temp control is not complex.