2014 MERCEDES-BENZ GL350 Engine Problems

HAVE A MERCEDES GL 350 WITH ONLY 63000 MILES, HAS MADE A SMALL RATTLE SOUND WHEN FIRST PURCHASED THAT I RELATED TO BEING DIESEL, RATTLE HAS GOTTEN WORSE, TOOK IN TO A MECHANIC WHO STATED TIMING CHAIN, I CALLED MY MERCEDES LOCAL DEALERSHIP AND SERVICE MANAGER STATED HE SPOKE WITH AUTO TECHNICIAN WHO "LAUGHED" WHEN HE HAD TOLD HIM MY CONCERN FOR THE TIMING CHAIN AS THE TECH SAID THIS DOESN'T HAPPEN UNTIL VEHICLES ARE VERY HIGH IN MILES LIKE 200000. THEY EXAMINED MY VEHICLE AND THEN STATED IN FACT IT WAS THE TIMING CHAIN AND QUOTED ME 75000. UPON FURTHER RESEARCH THERE HAS BEEN AN ISSUE WITH OTHERS ON THE INTERNET WITH THE GL 350 2014 SPECIFICALLY NEEDING TIMING CHAIN REPLACEMENT WHEN UNDER LOW MILES. CAR RATTLES WHEN STARTED, WORSE WHEN COLD, CONFIRMED TIMING CHAIN BY LOCAL MERCEDES DEALERSHIP.