A few other checks to do carrie out.
CHECK fuse F26 which should be 20.amp
And then relay K13,after these ,the screen heater switch itself .
i have taken the assumption that your model is the 1.6cc engine
ian, October 2009
Visibly check the wire connections at both sides of the window, in case one has come adrift. You then need a multimeter to check to see if 12v is appearing at those connections when the HRW switch is on.