Very much dissapointed with technical know how of ...

Very much dissapointed with technical know how of technicians. My 2015 klugger has aircon issue. Temperature gauge is showing 12-18 degrees difference between top and bottom vent and yet techician recons this is normal. They keep on saying that all readings are showing normal. Not sure what car does have different temperature reading in different vent. Very disappointed cutomer!!! Never going back and not recommended!!!