Is there a way to prove that a company sold your information to a third party?

If they themselves didn’t sell your info, they at least gave it out.

Its a “what did you expect.” But when these people call you, pick it up, let them identify themselves, and tell them to take you off their list, that you’re writing down the information about the time, date, the number on your caller id, and the company name and will call the Better Business Bureau if they call you again since you’ve asked that you be removed from their call list. You don’t have to do it, but odds are pretty good that they won’t call you again.

You can set them up, but it is hard to do after the fact.

One way to handle it is to use different versions of your name whenever you give it out: John Jones, John A. Jones, J. A. Jones, Johnathan Jones etc.

Then, if you get the strange calls, you can ask what they have for your name, and you can trace who gave it out.

In your current situation, not much you can do.

They don’t sell it; they are gathering the information for themselves to use for their clients. You never get things for free, there is always a price.

This will not be much help after the fact, but you can track some of this kind of behavior with an under used Gmail trick:

Here’s what you do. When you give your email address so a company, include their name after your name and a plus sign but before the @ in the email that you give them. You will still receive the email, but you will know where the company got your information from. For example, if you were giving your email address fluther, you would enter: Ansible1+fluther@gmail.com

Maximum PC covered this tip a while back as well. Their explanation may make more sense than mine.