Incorect account balance

I have been trying for several months to get somone within ADT to correct my account. A credit note was never passed, yet I get regular phone calls and incorrect statements wanting to know when I will pay my account. The contact names I received to help with my account does not respond to my request on e-mail. I would like to settle my account, but first need ADT to pass the correct credit. It seems impossible to get the correct person who can help me.