DTDC Courier & Cargo — careless service leading me a huge economic loss

I went to Jaynagar mazilpur DTDC branch 12.06.2018 to courier a amazon return with valid invoice and return request. The representative confirmed the address of shipment and made a DTDC plus receipt (DTDC COURIER consignment no V47346104 enclosed with this mail) and confirmed me that it will be delivered within 48 hours thats why charged Rs. 310 /- from me. Today(13.06.2018)I got a call from this branch asking to submit their receipt and take return the money paid by me as they are unable to send the item as the product is a STONE.
I went to their store but found the package was opened already. Then I contacted with the branch supervisor Mr.Anirban . He replied me that he was unable to tell any thing if I wanted to know anything then i have to visit their head office. Also blamed me saying that i am giving wrong information about the product price whereas i had company invoice of that particular product mentioning the price including GST and all tax.

I think this is a harrassment for me by your courier service. I should be informed first time when I have made the payments.