Incorrect debiting of my new homeloan account

The last progress payment was recieved 30/07/2015, Absa then send a sms that confirmed that the first debit order will go of on 01/09/2015. Absa then proceed to try and debit the amout on the 01/08/2015 but did not succeed as i did not plan for the money to be deducted from my account thus the amount was unavailible for deduction, this caused my account to be in arears... I have never had any bad credit record and none of my accounts had ever been in arrears... I am very disapointed in Absa and want this issue resolved asap, how can a bank state one thing and do another??? This was the last incorrect/unfair action by Absa that I am going to tollerate, I want this fixed asit was already reported by me on 03/08/2015 to a Marcia Serobatse and is still not rectified... Absa can count on me moving to another bank as i am fedup with incompotant actions like this.