My iphone 4 says i exceeded $20 in messaging but I have an unlimited texting plan?

My iphone 4 says i exceeded $20 in messaging but I have an unlimited texting plan. I don't understand how I could have exceeded my unlimited plan. What do I do?

It may be because you sent pictures with your text messages. I'm no expert, but that might be the case.
Yeah, those phone people are really particular.

You might want to talk to Telus, Bell or whoever you got your phone from. They'll explain it better than I can.

Call your carrier and ask, what makes you think people here know about your plan?