krukon, only our support can answer you your questions, as this is a billing related issue and these are not discussed on forums as they contain too much personal data involved.
Generally speaking though, some payment methods such as credit cards, may have a limit on them as to how much you can spend in a certain period of time to fight and prevent possible fraudulent activities. These limits do not necessarily have to be issued by us but by the payment provider itself but we also have limits on payment methods that allow charge backs. To the best of my knowledge, if you purchase huge amounts and spend lot of money in a short period of time, it may flag your account. These measures are not in place to hinder you but rather to protect you and your personal data from possible abuse.
As each case may have different reasons which can only be discussed with the account owner and initiator of the payments, please stay in touch with our support. If your answers are delayed or not received, please check the support FAQ in my signature as it may contain tips and advices that help to prevent these issues.
Murkalael, there is no such feature. To check which items you purchased, please check in-game in your inventory and item shop bag. The transaction history feature in Item Shop does work for some, but not for everyone, from what I know.