I previously wrote about a teenager who sent or received 14,528 SMS messages in a month. While in that case her family had unlimited text messaging, the subject of this story apparently had such plan on her phone, and racked up nearly $5,000 in fees with 20,000 text messages.

The exact total was $4,756.25. Cheyenne, CO resident Dena Christoffersen, 13, gave her parents, Gregg and Jaylene Christoffersen, a nasty surprise. The family had no text message plan on their Verizon service, and assumed that meant no text messaging could be done. Instead it meant they were simply charged for each one, incoming and outgoing.

Assuming a 31-day month, and taking into account the fact that most of the sending and receiving occurred in school, this amounts to 80+ SMS messages (in and out) each hour during an 8-hour school day.

One might imagine this somewhat affected her grades, and thus, in addition to the bad financial news, it turns out that Dena went from A's and B's one semester to F's in two months.

The prior story I wrote about occurred during winter break, so the teen wasn't affecting her grades.

Dad's reaction? He took a hammer to the phone. And Dena has been grounded for the rest of the school year. Fortunately for the family, Verizon has apparently dropped the bill down to a reasonable level, though what reasonable means is unclear.