This number keeps calling me day and night and never leaves message.  How can I get it to stop!

I would like to be taken off the call list for this company.

A guy named Jeff Daniels called and told me he was from diabetic supplies company and needed to ask me some questions.  He stated that our phone conversation may be recorded and had to ask alot of questions. Some the questions made me uncomfortable and  i told him i do not give information out on the phone.  He said he would call back at a later date and quickly houng up the phone.  Be careful do not give out any of your personal information.

calls, leaves no message.

They called me also at 7:58 PM PST.  I placed my cell phone on do not call registry and still I get calls?  Any advice?