Nykaa.com — refund not received even after they've picked up the product

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Nykaa.com

I have ordered pac hd liquid foundation 4.5 shade. And the order number was #[protected] on[protected]. When i received product, i realized that the shade i purchased was very darker so i asked them to replace. But they said they can't replace but refund my money after picking up the product. They picked up the product on[protected] but they didn't refund my money till now. I've sent so many mails to them but till now no action has been taken. Please help me get my refund. Thank you.