Thanks, 'Steele', for posting this. I posted the solution below on another site. It appears to scare these scammers...
The following levels the playing field a bit:
The company behind these calls is IXE Accelerated Financial Services, and they have a toll-free number: 1-888-226-5185.
Call this number from a public (i.e., pay) phone booth to voice your concerns multiple times. They have to pay significantly (over $0.50 per call) each they pick up because they have to reimburse the pay phone company on top of their regular phone bills!
This gets their attention. Ask them to remove your number. It's gratifying to know that they have to pay more than $0.50 to hear your concerns, and that you can make them pay more if they continue to harass you.
I answered THIS time - press 1 as this is your final notice to get your interest rate lowered. A lady wouldn't tell me WHO they were but that they were a "national" company to lower interest rates and lower your debt. I said "I still don't know WHO you are or what company you're with. She said we help lower your debt, I said "we don't have any debt." She responded by immediately hanging up on me.