Order not Delivered

I ordered a dress the 28th of feb and paid the Tax duties the 4th of march and i still haven't received my order. A few days ago i received an email from Shein(BUFFALO Logistics) requesting that i should pay Tax duties. I don't understand why i should pay for Tax again.I've send them proof of payment which there was no response to. This is very upsetting and unacceptable. The service that i've been receiving is very poor!!