I have successfully sued collections agencies like this. The Fair Debt Collection Act allows them to call you between the hours of 8 am to 9pm (your time). If you tell them to stop calling they don't have to, you have to either write them a letter and mail or fax it to them, stating that you don't want them to call you anymore. Or get a lawyer and sue them. I live in KY and the law allows you to record a phone conversation as long as one of the parties is aware it's being recorded (you). You don't have to tell them, but if you do record it, make sure you say you are if you want to cover your rear end if you live in a non-recording state.
Your letter should go like this:
Dear sir,
In accordance with the Fair Debt Collection Act, I am requesting you to stop all communications with me by any means or media. I don't owe this debt and I am not responsible for it. If you continue to harass me I will be forced to file a Federal Lawsuit seeking $1000 for each time you attempt to call me or write me.  I have retained the legal services of an Attorney and he has advised me to contact him the next time you attempt to contact me.

Sincerely,
John Doe

This letter works because I have used. This company tried to get me to pay an old $50k 2nd mortgage, I told them I was the victim of fraud by EMC Mortgage and I received a settlement in the recent suit agains this company. I really did, I got a big fat check.