If the diagnosis was correct, it would seem a bit premature for timing chain issues to crop up at 67K.

Extremely infrequent oil changes would assist in the wear and tear of the timing chain and tensioners.

And most if not ALL MB engines are interference engines...so chain stretch or cams out of sync is a recipe for severe engine damage if any of these components should fail...

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car