If you have a subscription with Microsoft & require support for your Microsoft 365 or Office 365 issue, you have 3 options:
- Online
The process of submitting a ticket for Microsoft 365/Office 365 issues through the Admin Portal is documented here:
https://docs.microsoft.com/en-us/microsoft-365/admin/contact-support-for-business-products?view=o365-worldwide&tabs=online - Phone
The phone numbers to call for support are available here depending on your geography. Note there are specific hours for Billing issues.
https://docs.microsoft.com/en-us/microsoft-365/admin/contact-support-for-business-products?view=o365-worldwide&tabs=phone - Microsoft Store
The process of scheduling an appointment with a Microsoft Store is documented here:
https://docs.microsoft.com/en-us/microsoft-365/admin/contact-support-for-business-products?view=o365-worldwide&tabs=instore
Service Descriptions for Office 365 Support including SLAs, case levels, etc. are available here:
- Office 365 Support – Service Descriptions
https://docs.microsoft.com/en-us/office365/servicedescriptions/office-365-platform-service-description/support