I have a 2015 Bounder 33C and the show is either cold or hot nothing in between. I ordered a replacement on the internet same quality. Who makes a quality mixing valve for RV's?
Pick one that you like from Lowe's, Home Depot, etc. Moen, American Standard, Delta, etc. and plumb it in to your existing piping (assuming you have access to it).
Plumbing fixtures are not RV specific, they are usually just cheap, plastic, light weight.