ADT not following CONTRACT

Hi. I would like for ADT to tell me why they are not following the contract I signed with them? My agreement with ADT is for a monthly debit order. All of a sudden, I check my debit orders only to realize ADT has NOT been debiting my account. I look at my ADT statement and it says I owe money (how is this possible when our agreement is that ADT must debit my account ???) This is low. I want to know what caused you not to debit your money? FIX THIS APSAP