Castle Rock Security Inc SAI harassment via collection agency, responding only by several phone messages Arlington Heights, Illinois

In August 2007, I had an alarm system installed in a rental house that I own in Staten Island, New York, by an alarm company, SAI, located in Orem, Utah, at no cost, but with monthly monitoring fees. 

In June 2009 I learned from the tenant that the alarm system was no longer functioning and that she now only had a cellphone and no in-house telephone.  So there was no longer a need for alarm monitoring.  She also told me that the alarm system itself had not worked for about a year.

I contacted the new alarm company, Castle Rock Security, and informed them in writing, first off, that since they were monitors of security systems, that they should have known when alarms were not functioning, and also that under those circumstances I no longer needed alarm monitoring and was cancelling my monthly online bill paying effective December 2009.

I received several phone calls from them in December and in January when payments did not arrive, and on January 16, 2010, I received a letter from a collection agency, Anderson, Crenshaw and Associates that if I disputed the bill I must notify them within 30 days since I missed two payments and now owed $89.98.

I did not reply to their telephone messages because I wanted to communicate with them only in writing so that I could produce something to show that there was dialogue between us. 

As I look at the letter from the collection agency, I notice that while it has the letterhead of Anderson, Crenshaw, it does not have their address, which I understand is in Dallas, Texas, but instead has the address and phone number of Castle Rock Security in the spot where the collection agency's address is supposed to appear.  It  appears that the collection agency did not send out this correspondence, but that it was sent by Castle Rock Security.

I have not received a written response to my letter, and they probably intend to continue phoning me and not send me a written response.  Today I received another phone call from them.

Castle Rock does not send information on its business practices.  I have no idea how long I am supposed to pay for monitoring, assuming  I have an alarm system to monitor.  However, they obviously want to receive payments whether there is an alarm system in operation or not, and they use the stationery of the collection agency to help them in this endeavor.