Strange it only affects the final checkout. I can log in fine, play no worries and can browse IM but not purchase. Doesn’t sound or feel like ddos
Try buying credit through the forum and browser in your phone. Only thing that worked for me. tried 3 different accounts, 2 of mine 1 of a friends through both item mall and forum with normal internet, wireless broadband and with/without VPN on two separate laptops. jump on phone, no worries