Managing personal Outlook.com account settings, security, and privacy
Sorry to hear you're having trouble.
If you still have access to your account then please double check if you can see the purchase at https://account.microsoft.com/billing/orders. While there change your password and/or email and turn on Two Factor Authentication if you don't already have it turned on.
If you cannot see the purchase listed then please contact your bank to dispute the charge as fraud.
If you have any more concerns regarding this issue then please be sure to start an online chat via https://support.microsoft.com and click on Contact Us then follow the instructions provided. Once you get to a person they may be able to help further.