Royal Enfield — low quality material

Sir/mam,
My name is jithin.
I have re himalayan m/c of 2016 model (Pb08dn1881). At the month of december 2019 re workshop jaisalmer changed camshaft and both inlet valve & outlet valve of the said vehicle. The products were brought from oem chennai (Invoice attached).
1. How could these engine parts of costly bike like himalayan damage with in 3 years and in 13000kms?
On 14th january 2020 again re workshop allahabad changed both inlet & outlet valve with original parts (Invoice attached). There was an unusual sound from engine and i ride the vehicle to the workshop allahabad.
2. How did this happen again after running 1000kms with new original engine parts and within one and half month?
My contact number is [protected]