Debit Order going through without notification

ADT Security repaired our alarm. We agreed that we would pay for the cost of the repair. When we enquired about the date that the debit order for the repair would go through, we were told that it would be at the end of April but instead of the debit order going through at the end of April, it went through on the 17th April (the middle of the month) without any notification and when there were not enough funds. This is not the first time that ADT has done this.