KTM Sportmotorcycle — regarding the poor quality of servicing at ktm servicing durgapur

I bought ktm duke250 motorcycle at durgapur on april 2017.
Recently from three months i am facing problem of sevior noise from back portion (Disk/chain).
I took my bike to serving centre durgapur two times. I m very dissopointed with the servicing. The quality is very poor.
Without solving problem they are telling that problem solved. But after servicing the noise is becoming very sevior than previous.
So please resolve my problem as early as possible as problem is very sevior.