When I got my litronics to replace my previous halogens I had exactly that same issue. Cleaning my old switch with electrical cleaner fixed it sort of, and a new switch fixed it completely and haven't had the issue since then, and it has been a couple years.
There appears to be an aftermarket switch now that wasn't available a the time I got mine (or else I didn't find it) so I used OEM. Here is the aftermarket one... maybe you can be the first one to try it
Ok I was going to post a link to it from Rock Auto but it is out of stock... The other one they have is Airtex/Wells for $89.99, I seem to remember the one I saw that time was like $25 or $35.
Well now after looking at the Porsche part, maybe $89.99 was the discounted part. I was sure at one time they had one for $25-$35
This part has got to cross reference with an Audi or VW part...