Complaint sub-issue: Charged too much interest

Received a line of credit from discover for their IT card with a balance transfer ( BT ) zero interest rate period of 18 months promo and zero interest rate on purchases for 6 months which would've end in XX/XX/XXXX and XX/XX/XXXX respectively. On Thursday XX/XX/XXXX I made my first of two BT of  {$3500.00} which generated fees of {$100.00}. On XX/XX/XXXX I made my second and final BT of {$310.00} which generated {$9.00} in fees. I made four ( 4 ) payments XX/XX/XXXX, XX/XX/XXXX, XX/XX/XXXX and XX/XX/XXXX of {$150.00} except for XX/XX/XXXX's payment which was {$140.00}. On XX/XX/XXXX, XX/XX/XXXX, XX/XX/XXXX and XX/XX/XXXX I made purchases from XXXX and XXXX XXXX XXXX of {$1100.00} ( XXXX ), {$1100.00} ( XXXX ), {$20.00} ( XXXX ) and {$1100.00} ( XXXX ) respectively. The purchase from XXXX of {$1100.00} made XXXX XXXX was returned along with the XXXX purchase of {$1100.00} refunds pending. Made my monthly payment for XX/XX/XXXX of {$100.00}. On Friday XX/XX/XXXX I made a XXXX purchase of {$340.00} returned and item from the purchase on XX/XX/XXXX for {$200.00} and made an additional purchase of {$310.00} so essentially my purchase total from XXXX was {$440.00}. On XX/XX/XXXX of XXXX  refund finally hit the card, all previous pending refunds already hit. Made my XXXX payment of {$150.00}. XX/XX/XXXX I had a XXXX charge of {$0.00}. Monday XX/XX/XXXX I made an XXXX purchase of {$200.00} and {$840.00} both purchases were refunded and refunds posted by XX/XX/XXXX within the zero interest period. That was the last purchase made on card to date ( Sunday XX/XX/XXXX ) and I continued making my monthly payments of about $ 150 monthly. 

From XX/XX/XXXX onwards I was charged approximately $ 50+ dollars in interest which seemed high since I should only have been carry a purchase balance of around {$1600.00} at an APR of 22.49 % according to my contract. however I said to myself discover would never cheat me my math must be off. some months passed by the interest charges still seemed high but I never got around to calling. 

On Friday XX/XX/XXXX XXXX XXXX  eastern time I decided to call discover and spoke to an agent who committed to getting to the bottom of the interest charges and confirmed that my BT transfer period was intact until XX/XX/XXXX. What was revealed during the call really opened my eyes as to how deceptive the practices of Discover really are. I learned that all my purchase refunds were going to my BT and not refunding my actual purchases that were made thus making me carry a higher ( more than twice the amount ) purchase balance ) thus allow Discover to charge me more interest since my BT was still in the zero interest period and my purchase were not. I asked to speak to a supervisor I got XXXX from Ohio employee number which he gave me was XXXX who in at first proceeding to tell me the agent before didn't provide me with the correct information and my refunds were not placed towards my BT but later backtracked when I went through the math which based on the amount of interest I was paying added up. however XXXX proceeding to tell me Discover was in the right and what they did was fair and nothing could be done. 

Discover is the worst financial company I have ever dealt with and I will never again after paying off and cancelling this card do business with them again and if you are reading to beg you to do the same. If my payments were going to my BT I would accept that, but to have my refunds for the exact amount from the same merchant go towards my BT and not my purchases in my mind is criminal and extremely unfair. 

I have attached files showing all the activity for this card. Name, address, telephone number and order numbers have been blocked out entirely or partially to protect my privacy.