Q: iTunes charged my bank instead of using my iTunes balance. Any chance in stopping this?

A gift card is not electronic media, so probably not eligible for using your iTunes Store credit.  iTunes Store credit balance can be used for all types of e-media, including songs, apps, ebooks, audiobooks, movies (and rentals), TV shows, etc.  Another example is donations to charity.  The iTunes Store recently provided a way to donate to support recovery from the catastrophic Louisiana flooding.  But you could not use your iTunes Store credit; payment had come from your designated Apple ID payment method.