The best way is to contact Microsoft Billing Support. The following page may help you see about troubleshooting Microsoft billing issues.
First you need to ensure the billing is from Microsoft, if not you need to deal this with your credit card service provider. If it is related to Microsoft, then you may raise the support request.
For Azure Support: https://azure.microsoft.com/en-us/support/create-ticket
For Microsoft Store and Billing Support - https://support.microsoft.com/en-us/microsoft-store-and-billing
Hope this helps