Undelivered Shein Item; Scammed

I ordered items over 80 pounds last November and I am yet to receive my item till today. My reference number is GSONAX61C00M2EN. I have been patronizing Shein for years now and I have never experienced such. I called Royal Mail severally and it seemed like shein never gave my item to them yet it says delivered on the app. I have waited so long for this to be rectified but nothing was done. I ordered 9 items, shein split my items into 2 parts and delivered just 1 item, 8 items are still with Shein. When I contacted Shein they claimed that my items had been delivered. I'm still waiting for Shein to update me about my order.