The message means that the billing system detected that you either have an incompatible data feature or missing a required data feature. An iPhone unlimited data plan was not meant to be used in any other type of phone. There should be no difficulty getting the compatible unlimited data feature (now grandfathered) added to the account after contacting CS. iPhone users who don't have a data feature get the same message when detected. Nothing new.
If I'm annoyed and you're annoyed, does that make us a paranoid ??
Sarcasm is a fine art...
"Don't believe everything you think"
It's not a matter of if you win or lose, it's how you assign the blame