Hijacking alarm code

I purchased an alarm system from B & M alarms in 2008 for $15,000. Along with the alarm system I subscribed to their monitoring service as well. The terms of the contract were 5 years to renew month to month unless either party was notified in writing by certified mail. In 2014 we cancelled service by certified mail letter. At that time we had experienced financial difficulty and an argument ensued as money was owed for a period of the monitoring service. In July of this Year I contacted a new alarm company to hook up the system to their service and were informed that the original alarm Company (B&M alams) had put a secret code on the system preventing anyone from taking over the service. We contacted B&M alarms and were told they will not release the code without payment. We offered a payment plan but they refused. My wife and kids are now living in a home without burglary, fire or carbon monoxide monitoring. We cannot afford the full payment owed but we need to be protected.