Although I am not a business, I got two call's the other day from some political person. When the caller asked if I had a minute to answer a few questions I said sure. (I was feeling pretty feisty that day and wanted to mess with them).
He asked something about how did I feel about President Obamas so and so, I said, "Who is that'? He obviously turned to his cronies in the office and said, "Hey, I have a lady on the phone who doesn't know who Obama is. Boy am I gonna have fun with her" at which time I laughed and hung up. Never got a call back.
The other one asked me if I had time to answer a few questions and first asked me if I would be voting Democrat or Rebublican in the upcoming election. I said, "Is this an election year"? He apologized for bothering me and said to have a nice day.
Since you are a business, it is rather tricky, but seems to me you are being harassed and as such, can complain to the Attorney Generals office in the state they are calling from. You just have to ask a few well placed and stated questions to get the information from them.