Hey there! Nice to meet you!
You can try using the username lookup from this link: https://support.microsoft.com/account-billing/forgotten-your-microsoft-account-username-b2049472-3b8f-27d3-61c6-67a668453f4c
However, the system can only show you a hint of the username once you have provided the verification codes through the account's security verification methods.
If you aren't able to locate your username, please try finding your Microsoft account username in other products or services associated with that account through this link.
https://support.microsoft.com/account-billing/check-products-or-services-where-you-used-your-microsoft-account-b3d49054-11d3-4e4d-9957-a3fa97925d59
In case you are no longer able to recover your account and your active subscription has automatic renewal enabled, you will need to contact your bank directly and request that they block all future charges from Microsoft. This will effectively cancel the subscription upon its next renewal and prevent any recurring charges.
You may also need to request a new payment method.
Thank you for your understanding.
Best regards,
Darhyl