Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
If you were charged for the Personal and Family subscriptions separately, when you switch from the Personal subscription to the Family version, you are charged for a full new subscription, and the remaining time on the Personal subscription is converted to the Family subscription on a 92% percentage basis.
Or were you charged twice for the new Family subscription?
Log into your Microsoft account (https://account.microsoft.com/services/) and check the expiry data on your new Family subscription, does that now indicate your subscription will expire in 2027 or 2028?
If the expiry date is listed as 2028 and you did pay for the new Family subscription twice, if you cancel the subscription, you may loose one year of the subscription, this forum is just a user to user forum, no-one here has any account access, you will need to contact Microsoft Support directly, try using this method to contact their support.
Go to this link: https://support.microsoft.com/contactus
Select Microsoft 365
Click 'Get Home Support'.
In the box provided, type billing.
Press Enter, then on the next page, scroll down and click 'Sign in to Contact Support'.
Navigate to Microsoft 365 and Office - Manage my Subscription.
Select the 'Chat with support agent in web browser' option