unwanted calls from this number from past seven days

I received a couple of threatening calls from FRS and they also left a threatening message on my parents home phone and at my brothers place of employment. I called the number back and only asked them for their mailing address. I promptly typed up a letter demanding that they send me information and verification on what case they were calling me about and I also sent them a letter stating that they were not allowed to call me regarding this matter. I sent both letters certified mail with return receipt. I received the signed return receipts back from them and I have not heard from them again. Here is the address to send them a letter demanding verification and/or a no contact letter. FRS (Federal Restitution Services) 5757 Main Street Williamsville, NY 14221

They call looking for a man named Keith, I am a female and my voice mail clearly states my name, and I've asked them to stop numerous time, and they don't.

when answered I say hello, there is no one there it clicks a few times and no one says anything so I hang up

This is a debt collector

they say that my friend has made a payday loan and they want to get in touch with her about her loan or take her to court. That if I don't get the message to her that I could be in trouble with the law as well.

Another annoying spam caller.

Got a call from this number at 8:30 in the morning on Sunday

wanted to update the credit card for my newspaper account