Billed for a router that Webafrica collected

Webafrica decided to invoice me R999 for a router they already collected. I reached out to their WhatsApp customer service and told them, that was incorrect. The agent told me a credit note was processed but to my surprise I was billed R999 today. Now they are telling me I must wait 7 days for a refund but it didn't take them 7 days to take my money. I don't have the router in question they collected it on the 15th of May 2025.