if the oil pressure switch was faulty i would have thought it would show with a scan on vagcom.
if the pick up pipe is block then its sump off job and you'll probs need the usual oil, filter and also sump gasket. But i doubt this would be the problem if its been serviced well and been flushed.
Are you noticing any smoke on start up and at full temp with foot to floor?
Also is oil making its way through the turbo oil feed pipe?