It's not an accurate correction. It's prepaid with an ability to incur a small amount of negative balance, partly for protection against downtime or data loss and partly so the systems can have some time to shut off (it would be hard to suspend service immediately across all services). However it is purely prepaid in that they don't provide a postpaid option.
That's a very uncharitable way of dismissing my claim that the parent claim of the service stopping automatically when you go over your credits is not true.
That's one thing. The second thing, I'm happy for you that you have more information about their pricing system than their pricing page and terms of service page state.