NGPAY - Defect in Samsung Mobile phone purchased from ngpay

I have received my samsung galaxy s3 i9300 pebble blue mobile phone 30/7/2012. Order no. 3286761475 dtd 25/7/12 for Rs.35010
as soon as I opened the box I noticed there are defects in the body colour of the phone.
I called ngpay immediately to register complain no. 858498. They told me to email them photos of defect, which I DID on the same day.

Then they asked me to get a DOA certificate from the samsung service centre. But the service centre said that they cannot provide DOA certificate for a body colour defect! They also gave me a service request form stating the same which I emailed to ngpay.

Now it has been 11 days , I have called ngpay about 10times but they refuse to replace my mobile without a doa certificate, which I cannot provide them

please help me get a refund from ngpay.
Thank you.