start with the easy / free stuff first before spending..

give you're boosts pipes a clean out and while you're there you can check the seals to see if there's any obvious leaks and check the turbo shaft for play then go from there.

Also make sure any other breather pipes are clear as a blockage could be increasing pressures and forcing oil past the seals whether they are good or not.

how many miles has it done ?? might just be due a refurb on age / mileage anyway.. Turbos don't last for ever unfortunately

2p