This is the second time it has happened. I locked the car and returned several hours later to find all windows open. Fortunately not in a public place. Is this a fault, erroneous key press or some other reason. Any ideas?

Pressing the unlock key continuously will open all the windows. When I've found all my windows open on a couple of occasions on my old O2 I've assumed this has happened inadvertently in my pocket, but not everyone seems convinced this is always the cause. There are a few threads on this site about this.

Same for me with an Octavia 2 FL. But not my Octavia 3 , as yet.

Yes it does happen with my Octy 3. What I think happens in my case is that the other keys on the ring can press on the unlock button while my in my trouser pocket. The VAG remote seems to have a good range, fine if you want to be sure you have locked the car after you have left it, but not so good if this happens. I think it can be coded out using VCDS.

Should be able to turn it off within the infotainment settings. 

22 hours ago, CCTaylor said:

The VAG remote seems to have a good range

A few years ago some colleagues and I did a test of remote range between a BMW 3 series, an Audi S4 and a Lexus LS400.

 

The remote range on the Audi was about 50% greater than either of the other two (over 50 metres) - and you could make it operate over an even greater distance by holding the remote against your head(!) when pressing the button .