Double transaction when buying motor parts

My name is MPHILO TSHIFHIWA ABEL on 30 November 2013 I bought car parts ot AUTOZONE (makhado) at the a value of R2061.61 and i used card to swipe and the transaction went twice (in other words i paid double) i went to AUTOZONE for inquiry and refund they send me to NEDBANK saying problems dont lies with NEDBANK and NEDBAMK send me back to AUTOZONE saying it not they problem.<br> I visited these institutions several times and i did not even get a respond or refund even today.<br> Please can you help me to solve this problem...