Hyundai i30 2009: Engine making noise

There has been a ticking noise in the motor in my 2009 Hyundai i30 from new. I was told it would go away after the oil change at the 7500 km service, but it got worse and turned into a loud tapping noise over winter. At 9800 km it was diagnosed with piston slap, claimed to be because the wrong pistons had been fitted at the factory. The motor was replaced, but the new one consumed oil and would intermittently make a loud rattling noise for about five seconds when first started. I was told that the noise was probably due to oil not getting to the timing chain for a few seconds on a cold start. I was also told that the tolerance for oil usage is 1 litre per 1600 km and we are now doing a 4000 km oil consumption test, taking the vehicle in every 1000 km to be checked. They also want the vehicle back after the check to see if they in they can find the cause of the rattle. Now they say the bore may have glazed because the run-in oil was changed at 5000 km and not 7500 km. I have asked for refund or replacement, which they have refused. What should I do?