Unpaid refund for over 4 months

Fedex cleared my Shein parcel in July 2025 , their online system had a glitch resulting in me paying clearing fees 3 times. Refund was promised to be within 21 days , till today i have not received my refund their feedabck keeps saying 21 days . It very frustrating and this point i dont know who must assist me as no one is responding to my follow up emails