I have read some very elaborate cease and desist letters through the years. Attorney, Dean Malone, advises to keep the letter brief and to the point.  I am in total agreement with Dean.  Thus, there really is not much to this letter.  The key is sending it certified mail return receipt requested.  The other key is noting the date that it is received and then making sure that the collection agency does not take any action that is not allowed by law.   Remember to never give them more than minimal amounts of information.  The Federal Debt Collection Practices Act gives you this right.

Note:  by sending this letter you do place the owner of the debt in a position to make a choice.  They could either give up trying to collect or seek legal action.  If this is within the statute of limitations period, where they can take legal action against you, sending this letter does create potential risk.  Please understand this action fully before taking it.