Terrible service

Their service is absolutely terrible! I have ordered Shein the 3rd of March. They sent me a message on the 19th saying they were delivering that day. My package never came and when I went to track my order, it said failed delivery. No-one tried to contact me whatsoever that day and I know they got the right contact details because they sent me a message on my phone number. Since then I have tried to contact them through calling, emails and whatsapps, but nothing. I don't know what else to do to get my package or get an answer from them. Terrible service!!