I can't download free apps from the App Store because I have pending unknown charges to pay

You have to work out whatever issue you have with unpaid charges with Apple. Until you do, you won't have access to the App Store for updates or downloading apps. They are NOT holding you hostage. You evidently owe them money. Contact Apple directly for help. You can use the Support button at the bottom of this page. If you are in the US, you can call them at: 800-MY-APPLE

No one here works for Apple as this is a user only forum.

You can pay the charges that are owed. Visit support.apple.com/billing to review your purchases, subscriptions, and billing details.

Until you find a way to pay for the charges, I don't believe there's anything you can do.

I'd suggest you contact Apple directly using the "Support" link at the bottom left of every page of these forums.

Click here.

Contact Apple Support