2016 sportsman 850 issue need help

I have a 2016 sportsman 850 HO bought in march. Ever since I’ve had it the exhaust pipe from the motor all the way back to the actual exhaust gets very hot and glows orange/red after riding it maybe 2 miles. It has even melted this black plastic piece near my leg multiple times dealer replaces it and "runs tests" says everything is normal. Obviously not the case. Is anyone else having this is Or have any suggestion on solving the issue? Really would like it resolved it can’t be good on motor and other components.