Since owning my estate I've noticed that the bottom half of my rear window and the rear quarter sections (Estate) don't clear when I switch the heating element button on. Is this a fuse problem? or something else?

 

Many Thanks

The side windows are not heated. The apparent elements are radio antennae. Likely a broken element in the rear window, you will need to inspect it closely to find it. You can buy conductive  paint to effect a DIY repair. I patched up an element on my Passat Estate around 20 years ago. Just found it in my touch up paint collection this morning.