My SHEIN Order Marked as Abnormal and Returned After 1 Month

I ordered from SHEIN, and it’s been a whole month without receiving any message from PTT about my package. According to the SHEIN app, my order had supposedly cleared customs, but two days later, it was marked as an abnormal package. I immediately called the PTT branch to check if they had any package under my name, and they informed me that the package had been returned 10 days ago without any notification to me. This situation is incredibly frustrating, and I have no idea what to do next. Can someone please guide me on how I can get my refund? SHEIN, I need clear instructions on how to resolve this issue and get my money back!