Hero Motocorp — Complaint regarding bike service

Address:

Karnal Devi Lal Chowk

I went today for service of my bike, they check my bike before servicing and said that chainset of your bike is not ok, and we have to change it.
I said ok but i changed my bike's chainset in last to last service so how its not working properly.
Then they said we will check.
After checking they said no sir we don't have any recod or replacing chainset
So you have to change it.
I said no please check it again.
Then they checked again and found that i replaced the chainset in my last to last service.
After that i told them to change it, but they said jo sir your chainset is ok.
What is this behaviour
They didn't change the chainset of my bike just because they found that i replaced my chainset from agency few months ago.
Please take action regarding this