DoubleDown Casino — no refund of money for something I did not get

On feb 6 I was charged 285.30 for chips in the doubledown casino. All I tried to do was purchase one package and kept getting error message so went on to bed only to wake up to a email where 285.30 was charged to my debit card and came out of my bank account. I about had a heart attack. I contacted doubledown and apple and received no help from either. All they tell me is they can't refund my money. I don't understand how they can charge me for something I never received. I am asking for your help. I don't know what else to do. I need my money to pay bills. I enjoy playing doubledown and do purchase chips from them but I sure never did these