National Diabetes Association repeated unwanted phone calls Internet

I initially contacted these people for information on diabetic supplies.  At first, they tried to push me to buy supplies from them.  I told them I wanted something in writing first so I could see more information about them and what they offered.  They had my phone number from my initial inquiry.

They refused to give me a return phone number, or to send anything in writing.

Since that time, they have repeatedly called my home phone, sometimes two and three times a day, even though I told them from day one that I was no longer interested since they would not send me materials in writing.  I have threatened to sue, threatened to report them to legal authorities, repeatedly told them to lose my telephone number and both my wife and daughter have told them the same thing.  Today, I received yet another call.  I recognized the voice as a woman with whom I had spoken to before and told not to call here ever again.  No matter what I do, I cannot seem to get them to stop calling.

I reported them to the telephone company, who advised me if the calls continued to file a police report so that they could put a trace on the call.  The police tell me that without that phone call, they cannot take a report.  I am at my wits end as to how to rid myself of these people.