Protection One Alarm Services attempts theft from customers! West Palm Beach, Florida

Our alarm system was installed in 1993, and Protection One bought the company and its customer accounts in, perhaps 1998.  We continued service after receiving the Protection One mail-out to existing customers notifying us that they would be providing service.  The service continued for 11 years, until November 2009 when we sold the house and relocated.  We called Protection One to cancel service as of December 1, 2009 and were told on the phone that there was not problem.  A few days later, we received a card to sign and return, which we did.  We have now been receiving collection calls from the company telling us that they charge a $100 cancellation fee. They also say that service is cancelled 30 days AFTER they receive the signed cancellation card.  In other words, as explained by the person with whom I spoke, they bill even when they do not provide service.  Their claim is that there was a contract for service, and that's where they get the right to charge the cancellation fee, and that they are not responsible to honor the original contract of the company whose customers they took over when they bought it out.