Nedbank refund process sucks

Why does it take Nedbank to refund a customer 7-10 WORKING DAYS after the company that banks with Nedbank made the mistake? According to Avis/Budget rentals customer service Nedbank takes 7-10 WORKING DAYS to process. What takes so long to process, they informed Nedbank on 8 November 2022 it's 18 November today and I'm still waiting for my refund!!!!!!