Disappointing service

I've purchased some items from shein on the 29th of June 2025. The transportation company is FedEx. They sent me a request today to pay for my customs which is R914.45. I paid and got the proof that paid was done which i emailed to them. They are still sending me emails requesting payment. My package has not moved because of this. I cannot get hold of the courier company it only takes me to a virtual assistant which is of no help Urgent response is needed to resolve this