Shein/Buffalo *****s Packages

Between Shein and Buffalo courriers my package got lost/******, Shein shows to have shipped it, however Buffalo, who is their courier/agent, can merely allege to have delivered the package even though their own tracking shows that it was received but not delivered, I am left without the ordered goods and being out of Pocket, Shein should take responsibility for the loss or order the courier to do so.. ***/*** Tracking number.