Double deduction for one transaction

I withdrew cash(R300) at a Standard bank atm though I use Nedbank, my statement shows thatthe amount was deducted from my balance on that date, then a few days later Nedbank again made a R300 deduction on my account for that very same transaction. I reported this on date 14/10/15 via the calle center they gave me ref number: ***3 and I was advised that this will be sorted in 6 working days of which it didn't happen, I called the call center again yesterday 23/10/15 and was told some story by an Amelia that I have to wait another 6days! I asked thati speak to someone who can make decisions but was told to wait and hope that it'll be sorted,please assist.