Why is the price I'm being charged different from the website?

From time to time we adjust our prices due to changes in our cost. For example, every year shipping rates are adjusted by the USPS.

When we make a change, our billing system doesn't go back and retroactively change everyone's account when we make an update, it only affects new subscribers. If you think about it, this makes a lot of sense - everyone signed up with an understanding of their monthly price.