i dont think it's actually the lock (as in pressing the fob or turning the key in the external key hole) causing the issue. after heating the external keyhole up with the hairdryer it does eventually allow the key to turn. my thinking was that the key still physically moves some catch inside the door, but it still looks to be electronically controlled somehow cos opening it activates the windows and locking even seems to turn on the alarm as the little light flashes on the window sill.
i think the catch holding the door may actually be frozen. it really does just feel like pushing on a locked door. next time i go to it i might actually try pushing it a little from the outside as i think there is a chance on other days when i've tried to open the door the catch may have sort of half come off but not fully came off because ice was making the door stuck and then i gave up and crawled in through another door. maybe trying to push the door "more" fully closed might make the catch fully spring into locked and then the handle might work properly again..... who knows. i just read that back to myself and even i didn't understand what i meant....

assuming it might be frozen forever i'm wondering how the stealer will actually get the door to open.... i presume the panels on the inside have access to a way of releasing the catch or something.
dunno whether anybody else here has done it regularly but i think it's actually quite hard work climbing in from the non-drivers door on the GTI! from the back seat the high centre armrest takes some effort getting over. from the passenger side the seat's side supports get in the way a little bit and the plastic thing around the heating/fan controls and the gearstick take some effort to navigate around.... and my dirty shoes inevitably go all over the upholstery and stuff. boo!

thankfully i'm a fairly average slim guy and only 5 ft 9 or something and i'm still flexible enough to slot myself in from any of the other doors. I presume it's also possible from the boot

but not tried that yet. as long as i can crawl onto half the back seat by folding half the back seat down crawl in and put the seat back up, i'll be able to crawl in the front. it doesn't bother me too much i can't use the driver's door, there are 3 other doors, and the boot! i'd have to be really really fubarred if all of them froze. As long as she can still take me to where i want to go for now i'll wait until this cold snap is over, might have to be after christmas. assuming it's still frozen i'll go back to the stealer. it'll be the first thing i'd go back to the dealer for after about 4700 miles or something. not an ideal issue to be going back for as i've driven other cars for longer that didn't have this issue, i guess it's just a bit of life experience.
the thermometer read about -6.5 celsius today - i'm in Greater Manchester
it's been colder on other days according to the themometer, seen -8.0 once on a 8:30am journey to work, but the door opened OK those days.
as for whiskey.... erm i don't actually have much alcohol... in fact none. i'm not really a drinking guy! gambling is my main vice... damn blackjack and poker..... all in with Ace King! oh, he had pocket Aces

along with nice cars and sexy women being other undesirable vices...
i'll let u know how it goes. thanks for the comments.