Amazon India — Not Refund of my exchange product

R/sir
I am purchased vivo v19 Mobile order no.[protected] on 18 nov 2020 which value 24990
I am purchased this mobile with exchange my old mobile which value 8200 and balance amount paid from bank account
Due to deleviry of defective item i returned my order then company refund only my bank account balance not my exchange value of my phone or not return my old mobile
I already contact with company agents many times but not refund yet
Company fraud by me 8200