Protection 1 Security Solutions

My problems started with this company about a year ago. My home security system alarm would go off waking us up in the middle of the night and constantly let us know there was no communication with the monitoring company. They changed the system twice and even installed a huge ugly antenna none of which solved the issue. I hired another company to install a security system. Protection one would not let me out of my contract so I paid the balance due in full.
When we cancelled our service we were forced to pay through the contract. They recently sent me a bill for monitoring service for March of this year and it totals $ 51.00. Their automated system calls my cell phone night and day. I have told them I do not have their service but they insist I owe them money for March 2013 monitoring and I have a copy of the bill. I don’t have any of their equipment and there is nothing they could possibly be monitoring. This is why I had another company come in because having no monitoring is having no security. I have three children and Protection One is gross in the their negligence of my families safety.
I called their customer service two days ago and they told me that I never stopped my automatic payment so this is why and they would correct the problem. Last night I got another call from the most rude and obnoxious person I have ever spoken to and she said because I never sent a letter of cancellation I owed the amount for the monitoring. It makes no sense to me. I have sent letters to the BBB but at this point I think I need to get a lawyer involved to stop the harassing phone calls. If I go this route I will be seeking damages.
Do not turst these crooks. The only 5 star must be the owner or an employee.