These XXXX keep calling from RANDOM phone numbers constantly. Sometimes it seems like different area codes as well. I think we have XXXX or XXXX different phone numbers for them so far. This is after we started keeping track. There have been dozens of hang up calls and calls from outside our area code with no messages left. 

I KEEP telling them they are NOT calling an individual but to the BUSINESS phone of a NON PROFIT ORGANIZATION. 
It appears they are to stupid to comprehend that simple English statement. 

They never state who they are, or the name of the person calling. If they do not hear a person answer they hang up and Voice mail messages from their numbers end up as " dead air '' and fill up our voice mail system sometimes preventing other legitimate callers from leaving messages. 

In an attempt to get more details of who THEY are, whenever i say that i am the person they are calling for, they tell me they are trying to collect a debt from a credit card, or other bill. The story seems to change each time. the dollar amount seems to change each time. 
I have not owned a credit card in possibly 10 years. Last vehicle was paid off about 10 years ago. 

With all of the internet scams out there, maybe these jokers are just professional scam artists? Hard to think otherwise knowing i have no credit cards or debt in 10 years. 

Any future contacts from them to us will be met with the most harsh and hostile reception possible.