Who called from 3302557500

Asked to put my number on their do not call list and the caller hung up on me!

They called. I said Hello, twice. They hung up on me.

they told me that if i didn't listen to them, i'd still get calls.  I hung up.

I get calls from this number at least twice a day for the last week (excluding Christmas eve and day)Every time I answer the caller hangs up.  I have tried calling it back which usually works but the number is disconnected.  What should I do now?