Buffalo lost my parcel

Between Buffalo and Fastway, theu lost my parcel feom Shein and not they say I must contact Shein to claim my refund. I am not certisfied with this. They are the ones who lost my parcel, why should it be me who contact Shein in for refund? Shein has closed my case stating that delivery was unsuccessful as if I was not available to receive delivery from Fastway, whereas I was available and they gave me wrong parcel and I was decent enough to contact them immediately to give them back the wrong item i have received hoping they will bring my right item soon, only to hear from Buffalo after few days that they lost my parcel and i must claim my refund from Shein. Shein does not give refund unless you are returning an item Buffalo please get me my parcel or pay me the money i spent to purchase the parcel you lost.