There are email spam programs that will send thousands of emails (useful if you know the service provider as you can email to say
[email protected] - for Verizon for example), which can be a full page of text, and there is this free Android app that spams a tel# by text message :
sms spammer - Android Apps on Google Play https://play.google.com/store/apps/details?id=ee.era.geek.sms_spammer&hl=en
It'll save you typing in the text over and over. Give them a taste of their own medicine. ;-)