Mechatronic is most likely. Very expensive but maybe you could find a used one.
There have been a few solenoid codes on those fixed by poor connections to those solenoids. Maybe resoldering cracked solder joints or other types of repairs like that.
I recently saw circuit plates available for these, but this would take advanced skills to replace. Used or new from Vw is probably the way to go.
Valve body rebuilders seem to have started offering these. I have no idea on price or quality.
Edit: I just thought that since you posted a "p" code that its possible there are other codes in there, and it could be that the trans has a internal failure along with the solenoid code. Might want to get scanned with vagcom before you commit to anything.