I have a 2016 Camry with manual havc controls. Today the knob for the heater seems to have broke. Hot is now cold and vice versa. Knob seems to just spin and not stop at all the way hot or cold. Is the knob replaceable or do I need to replace the controls? If I need to replace the controls how many hours of labor am I look at? Part seems readily available on Ebay for cheap.