Latest from myself. Cutting a long story short I have taken it to the dealer and they agreed it wasn't working. it has been replaced and I am now waiting for a chance to test. I will update.

Hi, @Pohsibj! What did they replace? What was the problem?

2 hours ago, Gabi4 said:

Hi, @Pohsibj! What did they replace? What was the problem?

They replaced the whole rear windscreen. Apparently there was power to it but it just wasn't working so that was the only option. I got the "...never come across this before" routine but we will see ! 

On 20/12/2019 at 20:41, Gabi4 said:

The heating in rear window started to work this week. In any case, I'll address the issue to dealer on Jan or Feb when I'll have to do the service.

Just for the record. I have just had my rear windscreen replaced under warranty after about 6 weeks. It was non functional. Dealer told me it was good I took it in straight away as the longer time goes on Skoda get a bit funny about replacing windscreens as its more likely to have been damaged after delivery.