Before they do any work on the car, and replace any parts, have them SHOW you the failed parts on the car. If the filter in the banjo bolt is blocked up, have them show you the clogged filter in your car. If the banjo bolt is leaking oil, have them show you the source of the leak.
If the turbo is damaged, have them show you that the impeller is notchy or seized in the turbo, and rotate it with your finger tips, as you should feel this quite readily.
Also, if the cause is the filter in the banjo bolt, contact Subaru, and ask them if they can provide you with Goodwill Assistance, as you have maintained your car well, and now you have a major issue with the car through no fault of your own, and it was caused by their faulty design. They have been helping a lot of other Subaru owners over the years who have asked.