I agree, the only time I've ever had a
problem with the heater was when my coolant was low.
Check this first. I actually had a leak from radiator, so if it is a persistent
problem get it checked out, especially if you are under warranty. Don't worry unduly though, it does need a top up from time to time.
The other thing to check could be the fuse, although it seems to be working ok otherwise?
Hope that helps