CHEYENNE — In one month, a Cheyenne teenager sent 10,000 text messages and received about the same — all while her family’s plan did not include texting.

That means the family’s provider — Verizon — charged them for each incoming and outgoing text message.

The girl’s parents, Gregg and Jaylene Christoffersen, thought texting had been disabled, so one can imagine their surprise when they got the monthly phone bill and it asked for $4,756.25.

“It just hit us like a rock, like you’re stepping into a bus,” Gregg Christoffersen said.

The bill was legit.

Dena Christoffersen, 13, had apparently been sending most of these messages at school. That’s more than 300 texts within an eight-hour period every day for the whole month.

Needless to say, it drew attention away from what she should have been doing: paying attention in class.

“She went from A’s and B’s one semester to F’s in two months,” Dena’s dad said.

Hours after the enormous bill arrived, Gregg Christoffersen took a hammer to his daughter’s phone.

He and Jaylene also grounded Dena until the end of school.

“I felt really bad, and I have learned my lesson,” Dena said, with her head down.

Since she lost her phone, Dena’s grades have gone up, and the texting is down to zero.

As for the phone bill, the family says Verizon has been willing to knock it down to a reasonable level.

The Christoffersens are asking school administrators at Johnson Junior High School to crack down on cellphone use during school.

See the smashed cell phone at 9News.com.