Xiaomi India — service charge

Address:

Barmer, Rajasthan, 344001

I purchased mi note 4 emei no.[protected] on 15 may 2017. Call not supported in this mobile. So i went to your service centre at barmer. After checking, he formated the mobile asked me to change the battery. So i purchased battery from him (Bar code wxin[protected] he charged service charge rs 413 (Other than battery charge 599 + gst). Why this service charge extra even if my mobile is in warranty period.