I bought 50 GB and I was charged $0.99 and $7.99. May I know why I was charged $7.99?

This is primarily a user-to-user support forum; other Apple users like you. We don't have access to information about charges to your account. See each of the steps in the following instructions. They include information on contacting Apple Support if the other steps don't help: If you see 'apple.com/bill' on your billing statement - Apple Support

Review your purchases, subscriptions, and billing details at support.apple.com/billing