Unauthorised Debting of my Account

On 2/5/2015 my account was debited with R2000 from RCCS BOS JHB #***. I did not authorised this debit and I want my money back. I've been with ABSA for over 25years and this is the first time something like this happens. I am not happy. I want my money back and I'm closing my account thereafter. Who authorised this debit order of R2000 on my account?? Its unexceptable!!