Product: Credit card or prepaid card

In XX/XX/XXXX, I used a new Wells Fargo credit card to finance a purchase through XXXX XXXX in the amount of {$6700.00}. This purchase was to have no interest if paid in full within 15 months ( by XX/XX/XXXX ). My minimum monthly payment was {$230.00}, however, I immediately began making monthly payments of {$450.00} ( which was above the monthly minimum ) to ensure this purchase was paid off within the 15-month timeframe. 
In XX/XX/XXXX, I used my existing Wells Fargo credit card to finance a second purchase through XXXX XXXX in the amount of {$10000.00}. This purchase is to have no interest if paid in full within 15 months ( by XX/XX/XXXX ). 
The following month, I received one statement from Wells Fargo. This statement included a single minimum monthly payment ( {$420.00} ) and my total balance on the credit card based on the two purchases I had made net what I had paid thus far. While my minimum monthly payment had increased, which was to be expected due to the higher balance, the statement did not indicate that each purchase required a separate minimum payment due each month, nor did it explain, or provide me with a way to choose, how my payment would be allocated between the two purchases. Without this level of detail, it was impossible for me to know whether or how my payments would be allocated. I continued to make monthly payments of {$450.00}, which exceeded the {$420.00} minimum monthly payment amount. My intent was to pay more than the minimum required on the two purchases combined, as determined and represented by Wells Fargo, so that I could maintain the benefit of the no interest provision for the first purchase. Based on the above and the fact that I made monthly payments in excess of the minimum monthly payment determined by Wells Fargo, it was reasonable to assume that Wells Fargo was appropriately allocating my payments in a manner that would maintain the no interest provision for the first purchase. 
On XX/XX/XXXX, after I believed I had made my final payment towards the first purchase, deferred interest was added to my account in the amount of {$1600.00}. When I realized this had occurred, I called Wells Fargo on XX/XX/XXXX to discuss what I believed to be a mistake. When I was told by XXXX XXXX sp? ) that it was not a mistake and a portion of my monthly payment had been applied to my second purchase, I offered to pay off the first purchase that day if the interest was waived. When my offer was rejected, I asked to be transferred to a supervisor. I then spoke with XXXX and again offered to pay off the first purchase that day if the interest was waived, which she also rejected. XXXX stated that I was required to make a minimum monthly payment towards each purchase as my purchases were considered two different loans. When I explained that was never communicated to me or noted in the statements I received, I was told that I should have known based on the increased minimum monthly payment, however, that monthly payment is not broken out between the purchases anywhere on the statements I received. When I asked why I did not receive two separate statements if these were two separate loans requiring two separate minimum monthly payments, XXXX stated that Wells Fargo sent one statement because the purchases were on XXXX credit card/account, furthering my point that I was under the impression I only had to make XXXX minimum monthly payment on the account. 
XXXX went on to say that my payment would be applied to the XXXX different minimum monthly payments, with any excess being applied towards my first purchase. Assuming ( because, again, this is not noted anywhere on my statement ) that explanation is accurate, the minimum monthly payment for my first purchase would be {$230.00} and the minimum monthly payment for my second purchase would be {$180.00} ( based only on the difference between my original minimum monthly payment and my increased minimum monthly payment as of XX/XX/XXXX, as this is not noted on my statement ). However, in XXXX XXXX, Wells Fargo allocated {$77.00}, {$76.00}, {$450.00}, {$450.00}, {$450.00}, and {$250.00}, respectively, to my first purchase. This clearly refutes XXXX statement that I had two separate minimum monthly payments and her explanation of how my monthly payments had been allocated. In XXXX and XXXX, the alleged minimum monthly payment ( {$230.00} ) was not applied to my first purchase, while in XXXX there was {$0.00} applied to the alleged minimum monthly payment ( {$180.00} ) on my second purchase. 
It is clear that Wells Fargo has arbitrarily applied my payments between my two purchases, which ultimately led to deferred interest being added to my account, and such interest has continued to accrue. 
On XX/XX/XXXX, I sent a XXXX demand letter to Wells Fargo stating that I suffered a loss of {$1700.00} ( the total interest applied to my account in XXXX ( {$1600.00} ) and XXXX ( {$56.00} ) ) due to their unclear, misleading, and intentionally vague credit card statements, and their arbitrary allocation of my payments. I also enclosed a check for {$280.00} labeled as payment in full for the balance remaining on my first purchase net the interest unfairly applied. Wells Fargo cashed this check, however, they also reduced my autopay amount for that month without my permission. It was my intent that the check, which was a completely separate payment, be an additional payment to my autopay, which had been set to pay {$450.00} each month since my account was opened. 
On XX/XX/XXXX, XXXX XXXX, XXXX Office Case XXXX at Wells Fargo, sent a response letter offering to waive {$1200.00} in interest charges if I made an additional payment, however, I contend that no interest is owed on my account and did not make the payment to accept the offer. I called XXXX on XX/XX/XXXX and left a message asking to discuss the offer, but she did not return my call. Of note, XXXX response letter did little to explain how my payments were allocated, other than to say that [ they ] applied [ my ] payments correctly. The letter goes on to say that I could have paid more towards my balance each month, however, I have no way to know and I highly doubt that any additional amounts paid would have been applied towards my first purchase to ensure it was paid off by the termination of the no interest period. 
On XX/XX/XXXX, Wells Fargo removed {$1300.00} in interest charges from my account, but added {$35.00} in interest. While I appreciate this gesture, I still insist that no interest is owed on my account. To date, {$1800.00} in interest charges were applied to my account ( {$1600.00}, {$56.00}, {$45.00}, and {$35.00} from XXXX respectively ) with only {$1300.00} waived.