The only complete way to turn off text messaging on a nextel phone is to actually remove what's called sms, unless this has changed since I worked for nextel customer care.

Sms(short message service) is on most if not all cell phones today. Now the problem with turning it off completely is that it also is what allows your voicemail alerts to come up when you get a message.

Sometimes if you are getting alot of messages changing your phone number will help, or temporarily turning off the sms feature and then reactivating it in a week or two can help.

I remember we used to have a heck of a time helping people who kept getting spammed because there really werent alot of options for us to use.

Definetly call in to customer care and let them know however.