Like Tyfighter and Chas83, I am a victim of Predicto.com. In my case, it wasn't my kids who were involved, just me. No one used my phone to sign up with Predicto. Predicto just started sending me text messages about a month ago. I had no idea who they were or what they were about, so I ignored them, even though each incoming text cost me 20 cents.
When my June bill arrived from Verizon, I had over $11 in text charges, even though I never use texting. A survey of my bill revealed $1.40 in text messages and a single "Premium text" for $9.99. I called Verizon to inquire and it was explained that this came from a "service" that plays some prediction game with a $50K prize. Verizon gave me the number for Predicto and I called them to tell them to stop.
The Predicto spokesperson (with a heavy foreign accent) told me that their records indicate that I had signed up for the game and even used a pin number they had provided me to do so. Well, that's a load of crap, because I never did any such thing, and no one else ever uses my phone (it's in my pocket all the time). It's possible that someone else signed up and used my number by mistake, but I certainly never signed up.
I don't blame Verizon for any of this. It was Predicto.com who nailed me. Fortunately I got away paying only about $12. If you find a $9.99 charge on your phone bill for "premium text" and discover that Predicto is behind it, the number to call is 1-800-360-0518.