Firstline Security Inc , & Security Associates International (SAI) Stopped sending bills after March 08, sent account to collection agency charging $1900 and put on my credit. Orem, Utah

Firstline Security installed an alarm system in my residence.  At first the bills were coming every month, then every three months.  I couldn't understand the last bill sent so I  attempted to called them to clarify discrepancies on the bill.  It took me approximately 20 calls to finally reach a live person.  When I did, I asked the young lady to disconnect the service until they could get themselves together because the bills were coming so sparatically.  She said she couldn't do that, another bill would come and  if there were any other problems to give her a call.  I didn't recieve another bill from March 08 until I recieved a bill in May 09 stating that I owed $1900.  This letter came from a collection agency.  I immediately wrote a letter to them explaining that I hadn't received a bill from them at all and asked them for a separate statement for the past due amount minus the interest charges requested, and regular monthly statements for payments be reinstated and the outstanding balance not be reflected on my credit report.  They returned another letter stating the validity of this debt was $1900 and the payment was due in full.  I replied back to them disputing the amount of the bill.  My neighbor allowed Firstline to withdraw the payments from her bank account and then another company came around the neighborhood again to change her security system.  I then called Mr. Ron Barker of Anderson, Crenshaw, and Associates LLC, 12801 North Central Expressway, North Central Plaza III, Suite 250, Dallas TX 75243 214-268-2980 ext 3305 to explain to him that I had not received any monthly statements from Firstline.  He was very smart on the phone which caused me to lose my temper because I want this off of my credit report.  I have not called him back at the moment because I will not allow him to talk to me like I am a child; I want this problem solved.  I should have done my research of the company first and now that I have done my homework, Firstline Security has a rating of F with the Better Business Bureau.  I don't know what else to do.  I really need someone's help with this matter.  I am thanking you in advance.