Product: Credit card

I paid the minimum payment on my due date XX/XX/XXXX and the remaining balance on XX/XX/XXXX. My account cycled on XX/XX/XXXX and I realized there were finance charges of {$240.00} eventhough I paid the full balance before the account cycled. I called on XX/XX/XXXX and the agent explained that I had to pay in full by the due date in order to avoid finance charges. I explained to her that policy is different from all the other credit cards I have and requested for a courtesy waiver. She processed the request through the system while I was on hold. When she came back, she stated that I will see a credit of {$240.00} on my next cycle date. 
When I reviewed my next statement, not only did I not receive the credit that was promised, but I received another charge for finance charges of {$240.00}. I called on XX/XX/XXXX and spoke to 2 agents. The first one explained to me their trailing interest policy however, I told her that I paid my balance by XX/XX/XXXX and then the full balance XX/XX/XXXX for the next cycle before the due date. She transferred me to a supervisor who repeated the same policy. I shared that I thought that I had 25 days for me to pay off the new balance before interest was received. She told me that the company has internal policies that they do not have to disclose to customers to include charging finance charges. I requested for a call back from a supervisor and never received one. 
I called again today XX/XX/XXXX and advised of the promise of the finance charges waiver and the deceptive practices shared on the phone and statement. 

Finance charges policy as written on statement : Paying Interest : Your due date is at least 25 days after the close of each billing period. If you have Pay Over Time, we will not charge you interest on charges automatically added to a Pay Over Time balance if each month you pay your Account Total New Balance on your billing statement ( or, if you have a Plan balance, your Adjusted Balance on your billing statement ) by the due date. If you have Cash Advance on your Account, we will begin charging interest on cash advances on the transaction date. If you have Pay Over Time Select : we will begin charging interest on purchases added to a Pay Over Time Select balance at your request on the date that they are added to your Pay Over Time Select balance. 
Trailing interest as written on statement : About Trailing Interest - You may see interest on your next statement even if you pay the new balance in full and on time and make no new charges. This is called " trailing interest ''. Trailing interest is the interest charged when, for example, you didn't pay your previous balance in full. When that happens, we charge interest from the first day of the billing period until we receive your payment in full. You can avoid paying interest on purchases by paying your balance in full ( or if you have a Plan balance, by paying your Adjusted Balance on your billing statement ) by the due date each month. Please see the " When we charge interest '' sub-section in your Cardmember Agreement for details. 

The way I interpreted these two policies is that I received the first interest charge because I didn't pay by the due date, but 4 days later on XX/XX/XXXX. At the beginning of the next billing cycle XX/XX/XXXX, I should have no balance from previous statement and only new charges. I should have 25 days to pay off the new balance which is by the due date before finance charges start again. I paid that balance on XX/XX/XXXX which was before the due date of XX/XX/XXXX.