Yatra Com - Refund injustice from Yatra

I booked QATAR Airlines for my mother to travel from delhi to houston and houston to delhi back ,the travel date were **th march **** & **th april **** respectively which costed me around *****/-. But due to covid international flights were cancelled from **rd march onwards. I cancelled my flight subsequently and sought for refund. After repeated mails for the last * months i finally got the refund but it is only Rs *****/-. My question is when the flight it self is cancelled why yatra is not giving complete refund. It gave complete refund to my aunt for the same flights on the same travel dates. While my aunt got a refund of Rs *****/- (Ref no ************) my mothers ticket got refund of Rs *****/- only(Ref no *************). Here it is note worthy to mention that yatra has once sent a credit note(attached below) regarding my mothers refund in which it is cleary stated the refund provided by airline i.e Qatar airline, is around Rs *****/-(my ticket price) but below that they mentioned airline cancellation charges and debited around Rs *****/-, while in real Qatar airlines are not charging any cancellation charges.