I have one heated seat not working, naturally it is the drivers side. The little pilot light in the switch does not glow. I could not find a blown fuse. Have not had time to trouble shoot further, could be an open circuit in the heating element.I have been through lots of rain with this one, but the passenger side works ok.
I had a similar problem with a 2014 car. It turned out that one of the heater cables had been pinched by one of the bolts that attaches the gearbox cover to the chassis, causing it to ground out. Those bolts were unnecessarily long which was part of the problem. I was able to trim 10-15mm from the bolts which still allowed them to serve their purpose without interferring with the wiring. If yours is the same problem then you should be able to spot it from underneath the car.
