You have about 3 months to pay a domain and most companies pay their domains at the end of the month or when ever they pay everything else, could be 15th as well. Many companies only pay their domains on the 3rd invoice. What makes mweb special that they have to pay 5 days after receiving the invoice?
Do your clients pay you before you send them an invoice?
If you look back at the records you will notice that their ICnt is never above 3(once), which means that they pay their domain on time and never as late as some isp's. So they've never received more than 2 invoices for a due bill before they've paid.