Peak Communications acting on behalf of Windstream Communication, saying we can save $20 total scammers! Nationwide

When Peak Communications called they used a blocked number. They said they were calling on behalf of Windstream Communications. They said we could save $20 on our bill. 

They basically acted like I wouldn't have any long distance if I didn't switch. They asked for the last 4 digits of my social security number. Now I know that was a mistake.

Is there anything I can do to shut them down or stop them?

I already called and cancelled but won't know until I get my bill.

If anybody calls from Peak Communications it is a scam!!!