Myntra.com — Serial number on the product is not matching

I bought a shirt from hnm from myntra..the quality was bad.. So i placed a return request. And when the delivery boy came to pick up.. The serial number on the product was not there or was not provided.. Tried every possible number on the tag.. But it was not succesfull..please do something about it at the earliest.. It was my first order from myntra.. And such a bad experience.. Fist it as soon as possible please...