Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Was this signed up directly with Msft?
If so, 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
If it was purchased via Apple App Store (I see you picked iOS as your question tag), you need to request it from Apple, not Microsoft, because the payment was processed via Apple.
Microsoft explains it here:
Apple's refund request instruction is here: https://support.apple.com/118223