Parcel missing during hijacking

I would like to lodge a Complaint about Temu shopping center.I have ordered clothes there but I didn't receive my parcel for the expected day I end up asking for refund but they didn't refund me the full amount price.My items costs R1.404 but they refund me R421.00 without any explanation. I am so disappointed about Temu,I need explanation why they didn't pay full price.