Myntra.com — myntra is not taking back the product, every time the courier boy comes and, says the serial number is not matching providing very bad service

Website:

www.myntra.com

I ordered a green white plazzo from myntra. I received the product along with two other products from myntra. All the product were very old looking so i decided to return them. The green white plazzo even had stitching defects.
First they sent an old product
Then when the courier boy came for pickup he picked up only the two except the green white plazzo saying that he does not have the return request for that.
Third.. When after two days a courier boy came for pickup he refused the package saying that the serial number is not matching. All the stickers and tags are intact.
I called service centre and explained everything. He assured me that the courier boy will come and pick up the product. And then after an hour my return request was declined.
I had to place another request for the same thing. I have talked to customer service many times.. They are just assuring.. Doing nothing.
The courier boy came the second time today and again refused the product. Today also i called the service centre.. They said that they have registered the complaint that the product is defective and will tell after 48hrs whether my request will be approved or not... So much hassle. She did not even tell that the product will be returned... Such a bad service they are giving.. Please help me get out of this and get my product returned.in the name of e-commerce they are selling bad product, giving bad service and cheating the customers.
Return i'd is [protected]
User id - [protected]@gmail.com
Mob - [protected]