Unfortunately, it's normal...
There are things you can do to combat it...
1. make her pay for the texts...unlimited or no, you have the plan for her and 22K is just a ton!!! that tells me she's not getting her work done.
2. Remind her or ask your pediatrician to tell her the hazards of it...there are kids who are having problems with carpal tunnel as well as thumb problems because of excessive texting..
3. Make her give you her cell phone after 9PM...if someone calls our home after 9PM? It BETTER be an emergency. My kids are not allowed to "chat" on the phone after 9PM...
4. Make one night a week a family night. Cell phone, computer and house phone free...focus on the family..if she can't do that - then she can't have her cell phone...she is part of a family and must participate.
I would keep the lines of communication open.
DO NOT use words like "YOU are..." use "I feel"...because the minute you put "YOU ARE" in the sentence - defenses go up and she's a teenager...so communication is EVER important!!!
GOOD LUCK!!