Debit order of R2600 unexplained

I opened a new account at Nedbank on the 28th July 2015, because I had problems concerning my other account with Nedbank. Within a few days on the 3rd August, a Debit order flew off my account totaling R2676.37. No notification was given as to who and why this debit order went off. Whenever I contact the call centre, they push me from pillar to post, and the same applies when I go into the bank, they put me on the phone with contact centres that do the same thing which is push me around! I want that Debit Order reversed, and the money placed BACK into my account! I have been with Nedbank since 2006 and this is the ******* service I receive from them! This is very agitating as I have been trying for several days/weeks/months to get my money back, with no success.