Response to your 3rd Party Collector Letter of Threat by Mail. 
The indictable offense of using the mails for the transmission of threatening matter. XXXX XXXX XXXX XXXX XXXX. 
XXXX XXXX, XXXX : XXXX XXXX XXXX XXXX XXXX XXXX XXXXXXXX XXXX ( XXXX ) XXXX XXXX : XXXX XXXX XXXX XXXX XXXXDear 3rd Party Collector, As I have NO Contract with you, you have threatened me by mail and if you proceed any further I will see you in court under charges of Mail Frauds and Threats. As of today I have presented a Credit Set-off Settlement to the " XXXX '' for the full billing amount, along with an IRS XXXX in full compliance with the XXXX Laws XX/XX/XXXX. They have 3 days to comply. 
If they should decide not to settle this matter I shall see them ; not you in court. For the fore mentioned charge of Mail Frauds. 
Thank you for your timeHonorably, XXXX XXXX XXXX