At any company doing Enterprise work, you don't cut off someone for non payment without Account Manager doing multiple phone calls to whoever you have contact information for, emailing everyone listed on the account and whoever opened a support ticket and maybe even putting a banner in the panel with "ACCOUNT OVERDUE, CALL US TO SORT IT OUT!"

Generally it takes 30 days past due and complete no contact for anyone before suspension.

No one pays $2m invoices with credit cards.