Hi,
Please use caution since it is possible you have received scam phone call that isn't from Microsoft. For this reason, I recommend you create billing support request. Billing support request is free of charge.
Please create a new billing support request using my instructions below.
Use this link to start the process:
https://portal.azure.com/#view/Microsoft_Azure_CostManagement/Menu/~/support/openedBy/AzurePortal
NOTE: The above link should take you to Cost Management -- Help -- New support request blade. If for some reason link doesn't work you may navigate there manually.
Fill out Summary, Problem type, Problem subtype, click Next. There will be a delay, then some recommended solutions will be shown. Do not click on any of the recommended options shown.
In the upper left corner, click Return to support request
Click Next to move to Additional details tab, fill out required information, email/phone, etc., click Next, review details and submit case. After submitting you should receive an automated email within a few minutes and a support engineer should contact you within 1 business day.
If you want you could select email as the contact method, that way you won't have to worry if phone call is actually from Microsoft or not.
Please click Accept Answer and upvote if the above was useful.
Thanks.
-TP