Product: Credit card or prepaid card

Weve used the credit card for several promotional interest free purchases in the past several years. I thought the payments that I was making was being applied towards the interest free promotions but recently found out that is not an automatic transaction. From that point forward, I made payments, waited for the check to clear my bank and then I called customer service to have the payment applied how I wanted it applied. I look at the credit card statement every single month and have spoken to many representatives over the past few months. The call that I placed on XX/XX/XXXX was the first time a representative advised me that there is a minimum due on another promotional purchase. This particular purchase was originally approximately {$17000.00} in XX/XX/XXXX. The promotion is interest of 7.99 % until paid off. The statement clearly states UNTIL PAID OFF. The statement does not say anywhere that there is a minimum amount that has to be applied to that balance first and the statement does not say what that minimum amount is. I have had enough of confusing statements and my promotions expiring so I have stayed on top of my recent promotion purchases. I made a call to customer service in XXXX to have the latest payment applied, I was given a payoff amount for each payment and made that payment in XXXX. I was shocked to see that my XXXX statement included interest, even though I had made every attempt to get it paid off on time. I called customer service and the representative told me that if I made a payment of {$220.00} plus {$220.00} that would satisfy the mimimal due on the promotion of XX/XX/XXXX as well as the two purchases of XX/XX/XXXX. Without the payment by XX/XX/XXXX, we will be charged interest on the interest free promotion. I made a payment on XX/XX/XXXX in the store and it cleared the bank yesterday. I called customer service today to ask them to apply the payment so that it pays off the interest free promotions. The representative informed me that I had other promotional interest free promotions that the payments was applied to instead of the ones I had wanted it to. I was told that if I make an additional {$120.00} payment by XX/XX/XXXX, they can apply that payment to the upcoming expiring interest free promotions. 

This is an ongoing issue. XXXX bank is unable to send me a printout of how the payments are allocated. The terms are not found anywhere on there statement, other than the current balance, original price, date of purchase and when promotion expires. I can not find anywhere on any statements where it says how much of a minimal amount is due on the fixed pay reduced APR promotion of 7.99 %. The statements are confusing and customer service representatives are also confusing. Not to mention, I dont understand why I have to contact them monthly to have payments applied. This forces me to spend too much time attempting to avoid interest and then I find out that all my time doesnt matter, they just want more money. My minimal amount due on XX/XX/XXXX was supposed to be {$280.00}. I sent a check for {$450.00} and now they want {$120.00} more. Needless to say, I find this all suspect and confusing. I think they should be forced to do a better job in writing to inform consumers how much the minimum is due on the promotions and how the payments will be applied.