I think the real lesson here is:

Never offer "unlimited". Because if you promise "unlimited" people will treat it as "unlimited".

The results usually aren't pretty.

EDIT: As the post below points out, telecoms are a prime example of companies getting burned on this.

My other go-to example would be all you can eat buffets. I know I've read about at least one lawsuit over people being kicked for eating too much at a buffet. (Or in the case of the only result I can get search engines to give me, too little.)

Of course, in the case of the buffet they're relying on the hope that people eat less than what they pay to get in on average. And since this sort of restaurant seems to stay in business that bet must be in the owners favor.

I hypothesize that business owners use this logic and offer unlimited only to watch it crash and burn all over their profit margins. From what I can tell, buffets appear to be the exception; not the rule.