Ask Me Bazaar — Faulty Power bank delivered

Hello, I ordered Mi power bank on COD and found it faulty but paid to delivery guy on 3rd July. after 15 min of delivery submitted my complaint online and called to customer care and lodge complaint and the guy has take my bank detail to refund the money in next 10 days but no refund received yet even nobody come to collect the faulty one then i called again on 10th July and the guy told me that someone will pick it up and then you will get refund in next 10 days. these guys are cheating customer. i want some action against them.This is really harassment for customer.