Yes, dealers. Although some independants can get hold of the downloads through other third party supportive means. Just depends whether the new release has been made available through that channel.
Your issue is to convince the dealer there is something wrong. They need to go beyond looking for fault codes. Not easy when there is no clue of a hard fault. And that is their time & costs which and they can't recover from VW(UK).
There is no specific Bulletin with the desciption you originally posted. As I wrote, there is a similar problem but not when stationary/crawling speed. Its a brief revving up when at speed, from overrun to accelerating again - "Delayed recognition of overrun/acceleration transistion in the gearbox control unit". But!, the circumstances that attribute to it, are being in a corner at speed.
As there is no direct fault or bulletin, they may charge you if VW (UK) do not agree to it being done. As it will most likely take a few minutes to download and then they need to test the Scirocco drives OK, so cost
1 hrs minmum labour unit ?
Updates are only really done if...... either there is a general need (VW/dealer campaign) or a specific fault is identified and part of the "fix" is a controller firmware update. Otherwise the controllers are left alone as built. Not a matter of going in and saying "I want" ...... That equals you pay!
I suggest you get a second dealer opinion and see if they can find anything. After all, at the moment, you do not have hard evidence supporting your problem.... in their eyes. So changing the firmware standard is just clutching at straws. It may be something new that VW are not aware of and is affecting just a few DSGs.
If enough people take their 'R' DSG in with the problem, then there will be a reaction centrally. Many bulletins appear with their first issue stating "postpone repairs" which means VW centrally are investigating and anything the dealer does will not be re-funded. Eventually, a solution appears. So the costs of rectification under warranty can be refunded to the dealer for doing the work on proof the fault is confirmed.
C.