In my personal subscription > Cost analysis tab, I can see cost by resources shown in screenshot in below. My subscription is pay-as-you-go type.
You may try creating a support ticket from the portal so that support team member can work closely and suggest. There are no charges for billing related tickets.
Edit #1
Adding answer as confirmed - For subscription sponsored by Microsoft, the balance can be checked here - https://www.microsoftazuresponsorships.com/
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