Product: Credit card or prepaid card

I have an Ethan Allen credit card issued by Synchrony Bank. The balance on the card has both promotional balances ( 0 % interest ) and non-promotional balances ( 29 % interest ). The promotional balance is new. When I make a payment now the entire payment is being applied to the promotional balance which is zero percent interest until next year, nothing is being applied to the interest bearing portion of the account. I called Synchrony. I was told a few different things by a few different people, but essentially it boils down to every time I make a payment I have to call them to tell them where to apply the payment. Fine. I did that. The payment however did not go where I asked, which was to the interest bearing portion of the balance. I called again. I was told that the transaction was not completed because the phone call was disconnected before the transaction was completed. That does not make sense to me. Then I was told that non of the payments were moved to the interest bearing portion of the account and nothing could be done retroactively. I was told I had to call within 10 days of making a payment, before or after to have the payment allocated. I did that. Then I was told, no, it had to be after I made a payment. I did that. I was told nothing could be done retroactively. That doesn't make sense. I was then told it could be done but would take one to two billing cycles to show up and that the interest may or may not be backed off. Then I was told that it would be taken care of when " the accounting department got to it. '' Are you confused yet? I am. I don't believe they are by law doing anything they can't get away with, but I do believe they are using unfair, confusing and antiquated practices and they feigning ignorance and blaming the confusion on the customer. Granted unfair is not illegal but I think they are pushing the envelope here. I have asked to have documentation about the conversations and payments sent to me and have been told that no one at Synchrony bank other than the legal department has access to email and that I should just " believe them '' when they tell me this will get straightened out. I do not. I have spoken to multiple customer service representatives, two account managers and am now waiting for " XXXX who is a People Supervisor '' to call me. No one has a last name and I was told that " XXXX the People Supervisor '' who is in charge of the account managers has " no more power to do anything than anyone else '', so what is the point of him contacting me? I can not reach anyone who has any " power to do anything '', which begs the question, what the XXXX is going on at Synchrony Bank? I have tried to figure this out myself but, if I can not speak to anyone who can actually assist me and get something done, what do I do? When I told XXXX, an account manager that I was not interested in apologies, because that's all I ever seem to get, I just wanted to get the issue resolved, I was told to change my tone of voice or she would hang up on me. I did not and she did. I believe they are intentionally making things difficult with the end goal being the customer gets frustrated and goes away empty handed while they rack up interest charges.