We received a charge on our bank account for apple.com 15.99 and do not know what it is. What number do I call to find out?

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

or go to Subscriptions and Billing - Official Apple Support

For phone numbers, see: Contact Apple for support and service - Apple Support