I have just noticed on the thread that you have linked to that apparently there are instructions in the manual to keep certain drain holes clear. If you haven't done that there may be that you wouldn't be able to point at Skoda or the seller has been the liable party.
If this is a common problem then it points to a defect and not a problem of wear and tear. If it is a defect then you have six years from the time the defect materialises or from the time you could reasonably have noticed it, to bring a court action.
I would suggest that you start finding examples on the Internet of people complaining about the same thing, get screenshots and also record the Internet addresses/URLs.
If possible get in contact with those people who have had this problem.
Don't worry about the one year warranty. It is a con. It doesn't interfere with your statutory rights. Did you buy the car from new?
Don't touch them owe me £500 since January 2019 make excuse after excuse. Seem they always have software problems sending money out. Keep saying they will call back or email nothing been chasing it now for 6 mths the phone staff always have the same banter we will chase it up and get back to you then nothing!