Error : workshop leave car in position P

I have an 2016 Octavia which keeps throwing the dreaded dsg error message and I can see that many people have replaced the micro switch assembly but no one seems to mention where I can buy one.

Any help would be appreciated - I have opened up the gear stick cover and have the reference number of "5q2 713 025 s" and cant find this reference number on the internet

Kind Regards

Mort