Amazon india - Amazon product fraud

Dear team Voxya,
I had received a faulty product (Mobile- POCO F*) from amazon. After I complained them, they told me to self return it to them, so i returned it via speed post. But amazon claimed that they have received a different product, and refused for for return or replacement.
Even after so many requests they didnt help.
I inquired them about what kind of product they have received, but they refused to tell me. after that I also requested them to return the whatever product they have received. Still they said they can not send it back.
This way they got to keep the money as well as the product.
I lost my hard earned ***** Rs. I had purchased that mobile for my brother. but now i cant buy another one.

This big companies live on the hard earned money of middle class people.

You are my only hope.

I beg you to help me.

please.