Amazon .in - Watch missing while return for pick up

Hi Sir,
I have taken Fossil watch on Amazon.in and as the dial is large, I put the return request and the pickup person came and took the watch. Later I got a mail from Amazon saying, they have received only empty box but the watch was missing. I have called customer care many times, they are saying give us the watch and we will refund.
I have questioned them, how can the pickup person take the watch blindly. Later I met the pickup person and he also confirmed I have given a watch and he placed it in his center (Amazon center, Alkapur). When I am calling customer care they are simply saying give **hrs. Please help me.