Amazon India — yamaha psr-e363 61-key touch sensitive portable keyboard

We bought the product on 17th july from amazon where in it was mentioned that product has 3 years seller/manufacturing warranty.
The product defect was found in 10 days when return window was over.
Contacted yamaha they refused to repair since the product was an online purchase.
We also had a warranty card received when the product was delivered.
Post yamaha's denial, we further contacted amazon for giving false information that product is covered under warranty.
Amazon asked us to provide in writing from yamaha that they do not repair online purchases.
We did the same and submitted the written reply on mail to amazon for almost 4 times.
They are just sitting idle begging for more time to resolve the issue.
The moment i took this issue over social media (Twitter) they became active and now they ask for service denial letter from authorized retailer.
Yamaha too has refused to give any sort of letter because they have replied to our query on mail and have also redirected to the terms and conditions on their website where it is mentioned that it is against yamaha's policy to repair products purchased online.
We have no where to go and i have been sitting on this issue making a fool of myself.
Amazon doesn't want to help in any possible way.
Here the consumer has been impacted between two companies yamaha and amazon.
I am attaching amazon's screenshot where it is mentioned that product is under warranty.
Also attaching the mail communication screenshot between my father and yamaha where in they have mentioned in writing that they do not serve products purchased online.