Coinut IS getting away with it. The comments on their thread indicate that they're calculating payments for the most recent term (during which the rate change was made) for the new discounted rate, not the full rate they started the term with.

Pulling this kind of shady shit is an easy way to motivate people to resign...maybe that's what Coinut wants.

If you're frustrated about this, let Coinut know. Here's there signature campaign thread: https://bitcointalk.org/index.php?topic=992660.0