First of all, do not speak with these people again. Put everything in writing, and keep copies of all writings in a file for later use. Write to them, tell them you dispute their accounts, and demand that they furnish verification of any/all debts they are attempting to collect. Also advise them that you are invoking all protections provided under the Federal Fair Collection Practices Act, and that they are not to call you at any time, at home or at work, and that all further communications must be in writing. All letters you send should be by certified mail, return receipt, so you have a record of all actions you have taken. If you stick faithfully to the procedures outlined, they will either provide you the information you lack, or they will eventually go away. If you do not, you can expect them to continue to make your life uncomfortable with their rudeness and continuing phone calls.