UPDATE - well, ok, I wasn't expecting that... new engine required...!!!!
Had a call from the dealer and apparently, something in the engine had snapped and then damaged another part of the engine (forgive my total ignorance in all things mechanical), resulting in a (technical term here) 'fcuked' engine.
Dealer has placed an order for a new one, but it's on backorder at VW

, and they won't find out for a day or two exactly how long it will take.