put my car in to get the clutch changed - all fine

one day later clunking starts
next it gets worse and a bit more frequent
next day its damn worse (car was driven hard)

today its pretty much constant.

Took the car back to specialist and found that its the rear propshaft knocking near the centre uv joint.

spoke to a few EVO rally specialists, Steve Hill Motorsport, Ralliart UK, Ears Motorsport, local ralliart mitsubishi dealer- and they suggested the uv joint has failed and was either damaged or agitated whilest taken apart or not lubricated enough on reassembly.
they also said these parts rarely fail and if so do so because of an impact (rock, big stone) or manufaturing fault (but is then detectable soon after production and doesnt happen 50k later)

so need to replace or recond. the uv joint, get a new bearing and get the propshaft rebalanced - not cheap and parts are mitsubishi only in japan (long delivery)

after getting the car back on tuesday i was taking it easy anyway for the new clutch and only really drove the car on sunday which certainly made the noise more frequent.

any ideas how i could approach the specialist in the hope that they will rectify this?