The most useless logistics service ever!!!

I had an order with Shein that I cancelled, the items wasn't delivered yet when I cancelled the order. They used Buffalo as couriers, which is the worst logistics company ever! When i check my return tracking number it shows 'pick up task delayed' even though I called them several times to advise that the package was never delivered. All they ever tell you is that your call will be escalated, which obviously doesn't lead to anything as I have never been contacted by them ever! When I requested a return with Shein I was told that this won't be long as I haven't received the items yet, its been two weeks since with no light at the end of the tunnel! I called them, emailed, whatsapp, facebook, live chat, everything! But still no help!