Thank goodness I was able to place early orders for 6 CGMs, 2 ToD Sorceress, 2 Zodak, 2 Stratos, 1 Faceless One and 1 Faker (7 consecutive 2-figure orders to avoid customs), because after that the website keeps refusing any further orders from me with a Payment Authorization Failure (even though I still have plenty of funds available to place well over half a dozen additional orders).
Called my bank and there's nothing wrong with my card. Finally made an international call to MattyCollector's Customer Service, and luckily I was directed straight to the escalation department, but the employee says there's nothing wrong with my account (it's not blocked or flagged or anything they can see on their system). He kept insisting that I checked that my cookies are cleared and that I tried with different browsers, but I told him I'd already tried those tricks a dozen times. He then suggested that I try using another card, but unfortunately I have none other available at this moment (if I had, I would have already tried that).
So his final solution was: Wait 24 hours and try again by then. Wonderful. So we're in the middle of this frenzied race-against-the-clock stock-clearance sale where any item may sell out at any moment and be gone for good forever, and their only solution is that I wait one whole day because their system suddenly refuses any and all of my further ordering attempts without any apparent motive.
I'll be paying a visit to my bank tomorrow first thing in the morning to see if I can get an additional virtual card issued before the flash sales on Monday, because I'll be majorly bummed if I miss Queen Marlena due to this Payment Authorization Failure crap.