@Priscilla Armstrong Welcome to Microsoft Q & A Community Forum. As you mentioned that billing owner has left your company, I would suggest you open support request from here. You can select the options as suggested below.
How do I change my Azure Dev Subscription billing owner so I can pay my bill?

Priscilla Armstrong
0
Reputation points
Hi,
Small business here and our dev lead left. I am unable to update the credit card info and pay our bill or make myself the new billing owner. This is getting urgent. I need to pay by 3/9/23. It's very frustrating to not be able to pay my bill. I want to get it back on autopay. I really need a solution, we can't have our website shut down.
Priscilla
{count} votes