PAID TWICE FOR ONE TICKET. RETURN MY MONEY, PLEASE!!!!!!

We booked tickets online for IMAX in Cape Gate. When entering my card details to make payment, the website indicated that the transaction failed. So, we tried again with my husband's card and only then did the site give us our booking QR ticket. But the next day my bank statement shows that the transaction did go through on my card. Which means we paid twice for one ticket. I have phoned and no one has phoned me back regarding this. This is concidered theft if my money is not returned!!!!