Product: Credit card or prepaid card

I've held an account with XXXX XXXX ( XXXX XXXX, XXXX XXXX, TN XXXX ) since XX/XX/XXXX. I submitted for the prepaid card in the amount of {$250.00} which was paid via check to open the account. 
Recently, in XX/XX/XXXX, I received a notice that my annual fee was overdue and incurred a late fee for a new total of {$66.00}. ( Annual fee is {$39.00} and the late payment charge was {$27.00} ) The full payment was by check and mailed, as this is the only option they allow for payment, and to the only address which is a PO Box as well. The next months bill showed my payment of {$66.00} and a new fee of {$38.00}. No purchases were made using the card in a very long time, and no " charges '' were listed on the bill. Yet my new bill amount was listed as {$100.00}. 
Admittedly and due to the fact I don't use this card, I hadn't been paying attention to the monthly paper bills because I wasn't using it, so this went unnoticed until yesterday XX/XX/XXXX when I received a " refund check '' from them in the amount of {$100.00}. I called the " customer service number XXXX to ask why I was receiving a " refund check '' and they shared that when they closed my account, without notification, this amount was to refund my remaining balance of the original {$250.00} of my money I used to secure the credit line. 
When speaking with Customer Service, the representative kept saying there were late charges and fees, but I asked why, he could offer no answer. So I was transferred to " Billing Dispute '' and restated my questions to which I was told that she was unable to " see that far back into the billing history '' I asked why the person handling disputes can not see 6 months of billing history to help resolve problems and I received no logical answer. In short, these fees, in ranging amounts of {$27.00}, {$38.00} and up to {$39.00} were being charged, all with zero purchases and a XXXX balance, minus fees that were being charged, only being late due to the first erroneous late charge to a total of {$190.00} on the bill due XX/XX/XXXX. I received my last bill that seemingly " erased '' those fees and brought my balance down to XXXX, my account was closed, without notice and was sent a " refund '' of {$100.00} or {$140.00} less than the amount I PREPAID to secure the card. I asked if they would refund the remaining balance of {$140.00} and the representative went back into the circular conversation of my fees, even when I asked, why would I have a fee if my total due was {$66.00} if I paid {$66.00}. They are trying to take advantage of people and it's upsetting to think of those people that would really be hurt by this dishonest behavior. Even using their own math, they claim I owed them {$190.00} but sent me a check for {$100.00} these amounts exceed {$250.00}, so the math isn't even logical. I've never heard of a company charging less than their billing statement and then on top of that, sending a refund check ... it just doesn't add up, that and the escalating " late fees '' that should have at a minimum been consistent or provided an update to terms fees and charges which they did not. 
Thankfully, my credit is great now, due to other credit cards and loans I've always paid on time with no surprises or tricks and gotcha tactics. To charge a late fee on a late fee when there is a {$0.00} is fraudulent at least.