Radio interference

First of all I'm new here.
Been lurking around the forums for quite some time now looking up things and ideas to give my car a little personal touch.Ordered some plastidip for the logo's after I've seen some pictures and howtos.

Now my problem, every time I turn on the rear wind shield heater it is as if I'm driving through a tunnel. I can steal hear what's being said or sang, but with a whole lot of static through it, all this disappears the moment I turn of the rear windshield heater.
Now it has been sent away for this to the dealership already last march, they replaced an electrical filter of the heater and fixed two tracks on the rear wind shield.
After this the problem seemed to be fixed, until a few weeks ago when this problem resurfaced again.
Would anyone have any idea what might cause this?

 

Mhh, I take it so far I have been the only one with this problem?

 

They used conductive paint indeed, and it has broken yet again as i just found out.

Also, would the electrical noise be cause by a lack of resistance from the missing tracks?

 

Mhh ok, then it seems the only solution is to replace the rear window. As they tried repairing the tracks twice now...

Dealership yesterday said that they would have to check who is going to get billed for this.
I'd say they should because they sold it to me like this saying it was a vehicle without problems, plus their guarantee service covers every damage to the windows except cracks.

I should be safe then, right?

 

Right, problem should be resolved in a few days now. Rear window is getting a replacement on the dealers costs.