What is the ruling on purchasing a "CashU" card for a price exceeding its actual value, and what are the implications of using the remaining balance if the sale is impermissible?

The transaction in question is a currency exchange, and it requires mutual possession (qabd) when currencies differ, though a difference in value is permissible. If the delay in transfer is necessary according to transfer regulations, then there is no harm. A delay in the bank entry is excused in ways that enable the beneficiary to take actual possession within the customary periods.