Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
May I know whether the subscription was purchased directly from Microsoft or through a third-party reseller/provider?
If this license is associated with a work or school account, your Microsoft 365 administrator may be able to review the subscription status in the Microsoft 365 Admin Center. If needed, they may also be able to create a support request from the admin portal to engage the Billing team for further investigation.
If the subscription was purchased directly from Microsoft, I recommend contacting Microsoft Billing Support and providing your cancellation approval confirmation, the monthly charge details, and the account associated with the subscription.
You can contact the Billing team via the phone support options available here:
Contact Microsoft Customer Support
If the subscription was purchased through a reseller or third-party provider, please contact them directly, as they manage the billing relationship and refund process.
The appropriate billing team will be able to review the subscription history, investigate why charges continued after the cancellation, and determine whether any refund may be applicable.
I hope this helps. If you need any further assistance, feel free to reach out.