Hi all,
**update**
sorry I haven’t replied back on this, so got the car back in early Jan 2024 with a replacement engine, clutch and dual mass fly wheel (as was easy to change during the engine change) and now runs and drives like a dream.
the guys at the garage didn’t really investigate the original engine anymore, so sadly it remains a mystery as to how it got like that.
just happy to have the car back and fully working, we are now mid March and all is well with the replacement engine now fully settled in.