What is the ruling on the increase in the exchange rate of the dollar when using an Al Ahli Mastercard prepaid card for purchases from Amazon; is it considered usury (riba) or is it permissible in Sharia?

It is permissible to use a prepaid Visa card, and there is no harm in exceeding the global exchange rate when purchasing with a different currency, provided there is immediate possession. This is based on the Prophet's (peace be upon him) saying: "(So) if these types differ, then sell however you wish, if it is hand to hand."