You can check and update the billing details of the account but it seems you cant get a hold of that ACC
I suggest you to Reach out to Microsoft Azure Support for assistance with resolving billing-related issues. You can log in to your Azure portal and navigate to the "Help + support" section, where you'll find options to contact support. Explain the situation, provide relevant details, and ask for assistance in resolving the billing issues associated with the former employee's account. ill also give you the support link below, take action promptly as this issue needs faster attention.
If this helps kindly accept the answer to close this thread thanks much