This is what I got when I googled the number. Y'all check it out.
http://southamericatravel.wordpress.com/contact-us/

called me three times, heavy accent and when I called hem back got a message all agents busy try your call again later.  They never did say what they wanted, informed not to call again after the last call at 10:30 pm.  Have not heard from them today

I answered and I only understood about every 3rd word that he said.  He knew my name and was saying something about health benefits.  Started talking about a "little known pain cream".  I hung up and blocked the number.

Do consider maybe getting a call blocking device or phone.. You can google them and many are around $60.00 or so.

Report your callers here:

https://www.ftccomplaintassistant.gov/#&panel1-1
https://esupport.fcc.gov/ccmsforms/form1088.action
https://complaints.donotcall.gov/complaint/complaintcheck.aspx?panel=2

By State DNC lists:
http://www.donotcallprotection.com/do_not_call_chart.shtml

I received calls from this number from 3:00pm until 10:40pm in one day. There was a total of 16 calls. I answered the phone, but received no answer. The caller also left no message. I am so sick and tired of these annoying calls!

Sir Bedevere is correct.  Since they are criminals, they will ignore the Do Not Call list, and any requests you might make.    YOU have to take action to do stop receiving their calls!  Consider buying a call blocker.
(google is your friend)
http://goo.gl/cdPm8O

You're dealing with criminals, and probably criminals who aren't even in the same country as you, so they have nothing to fear from lawsuits or law enforcement agencies, sadly.

They call repeatedly even after being told repeatedly not to call and take my number off their list. I have been told repeatedly that my number would be taken off but it's not. I have resorted to a stream of obscenities when they call and threats of suing them for harassment yet they keep calling. How clueless can these people be.

I have been getting calls from them from 10AM to after 10pm. Called back got recording

Same here.  I find it suspect that they are calling repeatedly, after 9PM EST.  When I call back, there is a very non-descript message.