Overdraft NOT approved

I want to know why I SHOULD PAY R315 FOR AN UNAPPROVED OVERDRAFT!!! If I didn't have funds available my unapproved date debit order would comeback. You cannot suddenly give me something that I did not approve!!! IVE NEVER PAID THIS!!!!! I WANT MY MONEY BACK!!! I NEVER GAVE YOU PERMISSION TO GIVE ME AN OVERDRAFT!!!