Product: Credit card

We made a purchase at Best Buy ( XXXX ), XXXX, KS XXXX Phone : ( XXXX ) XXXX in XX/XX/XXXX in the approximate amount of {$2700.00} and financed this purchase in their 0 % interest for 36 months promotion. To make payments, we were required to manually schedule each payment on their website, which we did. We then made a separate purchase approx XX/XX/XXXX in the approximate amount of {$800.00} and financed this purchase in their 0 % interest for 18 months promotion. During this transaction, the sales representative assisting us at the Best Buy store, as well as a supervisor, advised us that we were able to have two separate purchase promotions at the same time, and that when we made our payments, the payments would first be allocated to the first purchase promotion to fulfill the agreement and then subsequent payments would be allocated to the second purchase promotion. After carefully reviewing our account transactions, it appeared as though this was properly occurring. In XX/XX/XXXX, XXXX sold their Best Buy credit card account services to Citi. Our account was affected by this and payments were not being processed properly from this point on. Representatives that I spoke to on the phone stated that there is a possibility that during the merger/buy-out, our account could have experienced errors. While reviewing our account transactions, we made payments on time and adequate amounts to fulfill our financed amount within the agreed 36-month term. In further review of our account, payments were improperly allocated by the company ( or their system ) to the wrong purchase promotion, causing the agreed upon promotion to expire before the purchase amount was paid in full. In XX/XX/XXXX, we received a bill which added interest for the entire 36-month financed promotion period, as well as interest for the second 18-month financed promotion period. We have attempted to make contact with the company on countless occasions, spoke to countless representatives, first line supervisors, account managers and yesterday, XX/XX/XXXX, to an alleged " Customer advocate manager, '' who refuse to give us solutions or to make things right with their consumer. Multiple representatives have stated in recorded phone calls, that the payments being made should have been posted to the first promotion purchase ( the 36-month promotion in this case ) until it was paid off and then subsequent payments would go towards the next promotion purchase ( the 18-month promotion in this case ). Contact with initial representatives advised us that they were unable to review transactions or account status ' that were beyond 6 months, and required me to submit a letter in writing to account services about the error/discrepancy because they were the only department that could review this past the 6 months. We submitted the letter requesting them to review our account and requested contact via telephone. After not receiving a response, contact again was made with their customer service department. After no progress was made with the initial representative, I requested a manager. This manager advised that there had been a note made in the account that a letter was sent on XX/XX/XXXX and then read the letter to me over the phone, stating that the request for refund for the 18-month promotion was denied. I advised this manager that the promotion in question was the 36-month promotion because that is where they added interest to my account, which directly affected the 18-month promotion. He, again, told me he was not able to review my account past the 6-month timeframe and told me I would have to submit another letter to the same place, asking for the same review, specifically citing the 36-month promotion issue. He also stated several times that any person I spoke to, would deny my claim, just as this letter has. More to this, unable to add text due to max