OnePlus India — OnePlus bullet wireless Z

I bought this from Amazon.Earphones are in warranty period... As my location in not near any service center they're not providing pickup and drop service and when I asked them to kindly refund or replace the item... They very rudely denied and asked me to courier to service center where I enquired they do not have the product and when I asked for service denial form... They refused... I asked them to mail that they are not able to provide the same in written