Big Fish Slots Over Charged For Coins Refund

I purchased coins from Big Fish Slots in their happy. The  1st transaction of $4.22 was correct  ( I bought 2 $1.99 coins) then later I purchased  2 $4.99 worth if happy hour coins fir a total of $10.58. I spoke to apple support because they said I would have to talk to my credit card company. Because they say my security code is incorrect. The credit card company block the charge because it says I owe $29.60  fit a $10.58 charge. Everytime I deal with big fish I get over charged or I don't get my coins. I want my iTunes acct. straightened out because I do not owe thisninety. My credit card said if they have to pay it then I can go after iTunes and big fish for fraud . I don't want to have to do this I just want the problem fixed .  Thank you Ostsy