Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hello
If it was subscribed via Microsoft directly, since it is within 30 days, after you cancel it, please contact support to get refund assistance. Make sure you sign into your partner's account.
Go to https://support.microsoft.com/contactus, Type "Billing" and press Enter. On the next screen, click "Contact support" at the bottom of the page, then choose "Microsoft 365" > "Manage my subscription". You’ll then see the option to chat with a Microsoft support agent who has access to your account to help review the issue.
You can reference this detail step by step instruction with screenshots I posted in this thread: https://learn.microsoft.com/en-us/answers/c/2714817