Your dealer gave you hodgepoge (if correctly spelt). Some Seat dealers are the pits.
There was a production issue around week 39 or 37 which went on for two or three weeks where the control boxes fitted were problematic (see table below). Mine was one of them. It did effect all customers across Europe. The Seat German Ateca board did their own analysis. At one point customer services said there were over 160 cars effected which is a lot if that was the UK number or perhaps Europe.
Your garage must have its head in the sand if they don't know about this or don't want to worry with warranty repairs which says alot about them. They just order another control box in and fit it. That's about two weeks from start to end. A two hour job in the garage to rummage around in the boot. They told me there was some reprogramming so presumably they have to reprogrammed the control unit and other bits and bobs to introduce the component. That's why they told me it was two hours. I had a loan car out for the day.
There have been a few popping up on here with this issue with demonstrator cars or stock ones that have been built which to me all clearly date back to this period.
(Kindness got in front of me in my long answer

... )
Some threads for further reading
http://atecaforums.co.uk/viewtopic.php?f=8&t=328&p=2918&hilit=virtual+pedal#p2918
http://atecaforums.co.uk/viewtopic.php?f=8&t=273&p=2660&hilit=virt+virtual+pedal#p2660
As Kindness said.... if you get no joy put Customer Services on to them. I'm impressed with their approach of dealing with your problems, they liase backwards and forwards between you and your dealer till the issue gets solved. I'd forgot about this issue and thought I'd had three, no four, no wireless charger built into the car, no passenger footwell light, incorrectly fitted heated wing mirror and virtual pedal not working.
I'm looking for the survey the German Ateca board did where they pinned down the build weeks. They get their Heckklappe s sorted in October / November / December between pages 17 and 24.
https://www.ateca-forum.de/index.php/Thread/260-Elektrik-der-Heckklappe-teilweise-ohne-Funktion-Tipps-Tricks/?pageNo=23&s=a1809e65e026744cab43f2d8d1c80671ed1389cc
Page 16 and above these are the listed build week problems
KW 31 - OK
KW 32 -?
KW 33 - OK
KW 34 - OK
KW 35 - Error
KW 36 - Error
KW 37 - Error
KW 40- Error
From recollection mine was build in week 39. It's these cars in the UK that are being sold on where the control unit hasn't been replaced.