How on earth do you stop these calls?

They have called me several time a day for the past MONTH and I have never once answered.  Ironically, this started ever since I called cruises.com to get a quote on a listed cruise (that I didn't buy).  Did they sell my cell phone number??? Today, I've gotten 6 calls in less than an hour!  This is a personal and business cell phone and this is completely ridiculous!

Called twice today so far. Did not answer.

This number calls me every hour and I finally answered and told the person I was blocking the number and they hung up!

They called me eight times today. At least three were back to back. All while I was at work. I picked up three times and immediately hung up.  They never left a message.