Charged me twice, endless struggle to get my money back!

On Friday, I bought some clothes for my daughter at PEP Sanlam centre, Leraatsfontein. I came to the till and swiped my card and it said "declined". The lady then swiped my card again. I left and went to some other shops only to realize later on that the amount from PEP went off my account twice. I went back to the store and asked for the manager. She was very unhelpful and just said that I must come back on Monday. I explained to her that I simply can not just take off work because they had a system fault. I asked for her email address to which she rep**** that she does not have an email. I then told her that I would log a complaint on Hellopeter and she said I must do it maybe the problem will get solved then. So, PEP, where is my money?