D-Mart / Avenue Supermarts — refund issue

Hi,
I swiped my card on 10th nov in dmart but they didn't get the slip so they said me to swipe again so i swiped my amount debited twice. Then they said it will get refund automatically within 24 hrs but still i didn't receive my refund. I called to dmart many times but there is no use. They are very harsh if their servers problem means what should we do. They are telling i have to visit dmart twice once is for complain giving and second is for to collect letter. What is this non sense. What we don't have any another work.