Hello
Please go to https://account.live.com
Sign into your Microsoft account. Then go to Subscriptions. Do you have two separate plans? If so, you need to make sure you cancel one of them.
For refund, 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.