BCR still calling

If you sent this letter certified return receipt or some other verified delivery confirmation,then yes I think you could have a case for violating a cease & desist demand.

God! You should start recording the phone calls after checking on the laws in your state. They are giving you a verbal proof of their violating the fdcpa

You will find some good attorneys in naca.net

There are few attorneys in this forum also who can give you some guidance.

Record the next call from them, if legal in your state. File a complaint with their state's Attorney General, as well as the one in your stste, and consider suing them.

In my opinion you should maintain a track of the calls. You said that you have already sent the collection agency a Cease and Desist letter and they have responded to it by saying that they will not stop calling you. You did not mention whether you had sent the letter via certified mail with a return receipt request. If yes then you have the proof that the collection agency is calling you even after receiving the C&D letter. You can send the copy of your original C&D letter to the attorney general of your state and also seek help from the FTC.

Sounds like it could be a good case with the right proof.