Monotronics Closing account after contract expires in Arizona Dallas Texas

We started using Monotronics when my mother in law reached the age where she needed a way to contact 9-11 if she could not get to a phone during the periods of time when she would be in our home alone. Theft is not a problem in our neighborhood, although there is always that chance, but our motivation to purchase service from a security firm was strictly medical. After she passed on we decided to discontinue service. I called to cancel and was told that I needed to provide a written document via Fax with the reason why I was canceling the service. Of coarse the salesperson I spoke to offered a discount to which I asked, if the discount was available why was I being charged full price after years of loyal business. They had no reply. I wrote the letter as directed and attempted to Fax it to Monotronics for several days, from my home and my Bank after calling a second time to verify the Fax number. Finally after nearly a week we were able to successfully transmit the letter via Fax. Two days later I received an automated call in which the Calling person/robot seemed to wait several seconds before starting to speak,( I was about to hang up when they finally spoke), telling me that my letter had been received and that I now needed call dial 1 to continue the cancellation process. I was told that I would be billed another thirty days plus a pro-rated 6 days in a final bill. I called to cancel my service on July 15th and I am being billed until Aaugust 25th, for a service that was on a month to month basis after the initial contract long ago expired.