Shein.in — not giving refund of products

I had ordered several products from shien and decided to return 8 of them. They sent the delhivery company to take the returns and returned the same to them. However, they are not returning refund of 5 products claiming that delhivery return company didn't return 5 of them, despite showing them return receipt I had received from return company. They are continuously harassing me and asking me to co-ordinate with delhivery company(which they had chosen internally to take the returns). Such a horrible experience. It's a fraud company which just harass people.