If it was wired wrong when it was installed, replacing it won't help. It will still be miswired. They do need to diagnose the problem. Throwing parts at a problem is a poor, and expensive, way to fix it.
Bobbo and Lin
2017 F-150 XLT 4x4 SuperCab w/Max Tow Package 3.5l EcoBoost V6
2017 Airstream Flying Cloud 23FB