I second the tips from Diabeetus. I had difficult following the OP too. Punctuation is your friend.

Many fliers do not understand that there are different price tiers within classes.

If the lower price tier sells out, then, yes, you will pay a higher fare.

Non-FFs think that airlines "raise their prices" as the flight becomes closer. Those full-Y fares are always in there available to buy but few people want to buy them until all the T, S, K, L, W, G, ... are sold out (or expire, for categories that have advance-purchase restrictions). Therefore, the lowest available price on the market rises over time, even though the price of each code likely has not changed.

There are fewer of those tiers in Business or Premium Rouge, but there are some. You can get a lower fare if you are among the first bunch of purchasers. If others beat you to it, then you will be left with the full price.

As for the call centre and whether the ticket was void or not void, unfortunately on FT, we tend to either take complaint posts at face value as 100% true or deem them misrepresentations right out of the gate, but we will never know the objective story. What does "according to the credit card company" mean? i.e., does it mean the bank manager signed an affidavit saying the purchase was paid off, or did it mean more than one payment cycle has elapsed without a notification from AC about the purchase being voided. I recently had my card compromised, and two fraudulent purchases showed up on my card, which I went ahead and paid pending the investigation. Four weeks after the fraudulent purchase, "according to the credit card company" the purchase was authorized, but in fact, those charges were subsequently reversed to me and credited to my next payment, and the merchant or bank ate the cost. If there was a way to void the dresses, I am sure they would, but they can't. However, they can for flights. Obviously, the airline has reason to believe it will not be able to keep whatever the credit card paid them for those tickets. If the card was compromised but that purchase was legit, then the bank and airline have to sort it out. You can't badger a merchant into selling something if they are not getting a green light from the bank. I hope OP has cancelled that credit card and got a new one.