I would be thinking something to do with the injector servicing ? Sorry to hear of all the problems you're having mate, my son had similar issues a few years back with a brand spanker Hyundai i30 diesel, complete clutch, pressure plate and flywheel overhaul @ 1700kms, serious water leak in boot, started the car one morning to a cloud of blue smoke, clutch started chattering again @ 5,000 kms Hyundai's response, we'll sort it for you you have 5 years warranty
It's not what you expect when you buy a new car and especially a diesel for what you hoped would be reliable engine longevity :( I'm guessing you will be wanting to get rid of it by now, I went to the Hyundai dealership with my son and asked them to consider buying it back (which they did), we lost a couple of grand on the purchase price, they put it back up for sale in their yard, it sat for nearly 6 months before they eventually sold it, saw it around a couple of times with some old fella driving it. A few months later it was back in the lot of the Hyundai yard again
Best decision we ever made was biting the bullet and getting rid of the lemon