Oil filter adaptor flange

My 2008 GTI is leaking oil at the Oil filter adapter flange. I'm told it must be replaced because it's plastic.
Questions;
Does it indeed need to be totally replaced or can the seals inside be replaced?
Is this a difficult DIY job?
If taken to a mechanic, is it a 2 hour job for cost of labor?
Is an aftermarket part ok or should it be oem or is there an upgrade?
Thanks

See here as it was just discussed:
http://www.golfmkv.com/forums/showthread.php?t=199638

So, first I should pop off the cap and make sure the bleeder valve is sealed? Had my oil changed just before oil spots started appearing on the driveway, which my dad was not too happy with :-(