One more thought...
Wonder if the dealership is just shooting in the dark...many dealers never sold a gen1 car....
Bet the sound on the 2007 gen1 car (if it was a stick) was a bad throwout bearing(in this case dealer is truly bad)....
That or the head+block had both been decked beyond spec by a previous owner...resulting in a loose chain...fix is a thicker headgasket and maybe even adding a washer to the timing chain tensioner...yes..folks have done it...heck NATHAN'S car gnat over on another board has the same issue....
But fixes a newer factory "trained" tech might not try, cause no car is EVER mechined out I'd spec in the dealer world.....lol...
Good they worked hard to make you happy....a r52 is so different from a gen3...makes me wonder...sure they are kinda the same shape....

 

My bad, I didn't notice his 2007 was a convertable and forgot that the Cabrio didn't get the N14 engine in 2007 only the HB.

 

My 2010 R56 with 58,000 never used any oil & oil changed at recommended 10,000 miles.

 

My Orange One,

Was your 2010 a base or an S?