Product: Credit card or prepaid card

CHASE bank failed to follow the CARDMEMBER SERVICES AGREEMENT when applying credits and payments to an account that has two interest rates. 

Furthermore they refuse to amend credit reporting on the account to elucidate that there are two types of account. One type is a protected or safeguarded balance that is subject to the original fixed rate which can not be charged to or balance increased. Then there is the new variable rate account that actually has a revolving balance. 

Essentially there is no difference between a fixed rate loan and the fixed rate safeguarded and protected balance. That balance is on a fixed repayment plan and the credit reporting must reflect that. 

Excerpts from the CARDMEMBER SERVICES AGREEMENT : " We figure the daily balance for each transaction type as follows : We take the beginning balance for each day and add - anyinterestchargefromthepriorday ( knownascompoundingofinterest ) and - anynewtransactionsorotherdebits ( includingAnnualMembershipFees, transaction fees, Penalty Fees, any other fees and unpaid interest charges ). 
We subtract payments or credits, and treat any net credit balance as a XXXX  balance. 
The result is the daily balance for each type of transaction. '' " We figure the interest charges on your account as follows : To get the daily interest rate for each type of transaction we divide the APR by 365. We may combine different transaction types that have the same daily interest rates. 
We multiply the daily interest rate by the daily balance for each transaction type for each day in the billing cycle. 
We add together the interest charges for each day in the billing cycle for each transaction type. 
If any interest charge is due, we will charge you at least the minimum interest charge shown on the Rates and Fees Table. '' " When you make a payment, generally, we first apply your minimum payment to the monthly obligation for any Flexible Financing Offer balances with special payment obligations which require repayment of the balance over a pre-selected number of billing periods, and then to the balance on your monthly statement with the lowest APR. 
Any payment above your minimum payment would generally then be applied to the balance on your monthly statement with the highest APR first. 
If you do not pay your New Balance or Interest Saving Balance, as shown on your statement, in full each month, you may not be able to avoid interest charges on new purchases. '' In the definitions there is no delineation or difference in how a return by a vendor is processed as a payment or credit vs a payment made by the member. As such both types of credits are equivalent and should be applied to the balances of each type of interest rate accordingly as given above. 

This was not done by CHASE. I do not know what they did or how their algorithm is not calculating the interest rate properly. The result is that why we made a large temporary purchase on the card and then had that purchase refunded by the vendor the new higher variable interest rate balance was not credited for the payment made. As such CHASE has been over charging interest since they began the Variable rate in XX/XX/19. 

This is entirely likely not just a me problem in that whatever computer program they use is used on every cardmember who previously had a fixed rate. 

As Such they have over charged me interest and as a result the balance difference between what they show and what I calculated is {$6600.00}. 

I have attached statements from a few months before the change in terms. 
I have attached a pdf spreadsheet credit and debit ledger showing the daily balances for each day of transaction on the account. 
I have also attached the XXXX spreadsheet to review the calculations I have attached correspondence from CHASE I have attached the cardmember services agreement I have attached a screenshot of todays balance.