Poor customer service at Buffalo international Logistics

I bought clothes online from SHEIN in September and as always when clothes are big or small you return them. The return address BUFFALO International Logistics based in Kempton pack and this was done through Courier guys who provided a receipt with tracking number and the person who signed for the parcel. For the past month i have been phoning as the system on SHEIN shows that the parcel has not been returned for the refund. I been asked for the Buffalo number and the Courier Guys tracking number of which i provided. I got an email to send i must contact the supplier , but contact of supplier is through them and it shows the parcel was not logged onto the system. I am still waiting Since Sept and now we in November for a refund which is supposed to take 5-10 days.