That drives me insane. At one point I ended up having to argue with many service reps over a toll pass that I was unable to pay. The online payment site wouldn't allow me to access it due to being in the Carribean, in Puerto Rico actually which is still part of the US.

I ended up in a loop talking to various CSRs over a few months as each time I called they wouldn't let me pay over the phone as my address was in Puerto Rico, and kept telling me to pay online, which I couldn't do. Kept getting passed from one rep to another, escalated to no effect. Had call-backs from "supervisors". Eventually I was back on the mainland for holidays and managed to call back and get someone to drop the late fees, then paid online.