@gskumaar12...
Did you ask the seller before your returned the item if he is going to reimburse the return courier charges to you ??, if not then why have you not cleared this point with the seller. Many people misguide buyers here on the forum with their half knowledge about the working of ebay, many sellers are also not fully conversant with all ebay rules too so it is a bad situation.
The proper way to do things is that you should have asked your seller about the reimbursement part and your seller should have guided you to ebay customer care wherein you mention that the product is defective and you want to return it for a replacement and only when ebay asks you to return the product to the seller then you send the product back and after that you send a scan copy of the courier slip to ebay to get your reimbursement.
So learn how to shop online, always buy from good old reputed sellers with good sales, check feedback quality and you will be happy.
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