Refund never paid

In April 2025 I ordered shoes from Shein and on arrival they were small. I requested refund but was told that they'll send Buffalo Couriers to collect then they will refund. Till now they have not collected the shoes. I wrote countless emails and WhatsApp to both Shein and Buffalo Couriers but all they do is to send me the same automated messages saying they've received the message. Worse they don't have direct line where I can contact them. I think Shein and Buffalo Couriers are colluding. I'm disgusted by these companies.