Been calling for several times a day.  Leaves no message.  I scan all calls.  It has to be a robo call.  No background sounds

This number keeps calling me, I don't want them calling anymore. Calls about every hour

Have you considered obtaining a call blocking device, app, or phone?  Google (or your favorite search engine) IS your friend!
Realize that the Do Not Call list is NOT a call blocker!

Here are some tried and true methods for reducing or eliminating repeated spam / scam phone calls:  Click on the Info button, below, to see them (Javascript required)

InfoWant to stop repeated telescam phone calls?
Try these alternatives:

1.  Do not answer the phone if you see an unknown number on your Caller ID ... let it go to answering machine or voicemail.  Many telescammers hang up after three or four rings.

2.  If you have a smartphone, get one of the inexpensive or free phone blocker apps at your online app store, and learn how to use it.

3.  If your cell is not "smart", read the manual to learn how to set up a "group".  Assign the scammer's phone number to that group.  Also assign a "silent ring" to that group.  You will not hear future calls from that number.

3a.  Alternately, assign a "silent ringtone" as the DEFAULT ringtone.  Then, assign your favorite ringtones to friends, family, contacts, businesses, etc.  That way, you will not hear your phone ring, even if the scammer changes numbers!  (Disadvantage: if you forget to whitelist somebody, you won't hear their calls, either)

4.  For cell phones or landlines: Contact your phone service provider.  They may have a facility or method to allow you to block numbers.

5.  If you buy things online, you might want to google "phone blocker" to see what devices or apps Amazon or other sites have to offer for landlines or smartphones.

6.  DO NOT call unknown numbers back without checking who called (800notes is your friend)! All that does is verify your number is "live".  Instead, read this:
http://www.consumer.ftc.gov/blog/one-ring-cel ... ing-your-wallet
If you want to report potential fraudulent or scam calls, here are two pages of links to (mostly government) sites in Canada and the USA were you can report those scams, or learn more about them.

Look here first:
http://800notes.com/arts/I2neMkbUAAo/where-to-report-phone-crime

If the reporting site you wanted is not in the above list, try this one:
http://phonehelp.2truth.com/complaint_sites.html

Please reply to this post, to let us know you read it, or will try some of the suggested methods.

They call my phone about 4-6 times a day from 10am to about 6pm and never leave a voicemail.

Calling but not leaving a message. They have called numerous times.