unauthorized charges

I was signing up fro the rebate from Alltel then had to submit a pass code from the internet on the rebate directions. Next thing I know I started receiving jokes on my cell phone. I texed back put me on the do not call list. a text message came that said subscription renewed @5.99 /weekly or 23.96 a month. I texted back refused. They sent back a text that said sorry ur command is not recognized. This is a bogus way to add charges. It should be told to others that it is a scam! I would appreciate the opportunity to cancel this ASAP.