Why does Avant card allow limit increase online but not a decrease?

[brokeagain]

I recently required a temporary increase on my avant credit card and I did it via their website. I now want to decrease the limit again but the website doesn't allow me to. The first link states that I can increase or decrease your limit but when I try to decrease I get a message saying that the limit requested cannot be less that the existing limit. This is very frustrating.

If I call them, it'll cost me!!