How can I make these online colleges stop calling my personal cell phone?

I filled out a thing for information about colleges online, thinking I would get something by mail, or email. It required a phone number so I put my cell phone since thats all I have, but within an hour I started getting calls. It has been 3 weeks, Im still getting between 10 and 20 long distance calls a day, from various numbers claiming to be colleges, my cell phone bill is through the roof. I put my number on the do not call list, but I guess they arent considered 'telemarketers' because they have not stopped, or even slowed. Help, please how can I get them to stop calling my cell phone? The main one is called kaplan university I think?
I forgot to add, I have t-mobile..is there any way they would block these calls for me, or am I just going to have to get a number change?