Is it permissible for a Muslim to purchase items for others using his own Visa card and take a price or an increase above the price of the purchased commodity?

If credit cards are free from prohibitions, then it is permissible to use them and to purchase goods for others with them in three scenarios:

1. It is a form of exchange (sarf), whereby you pay the price of the commodity with the card and the buyer gives you a substitute with an increase. This is permissible if the currencies differ, provided that possession (qabḍ) takes place in the same session of the contract.

2. You act as an agent for them in purchasing, in exchange for a known fee.

3. You purchase the goods for yourself and take possession of them, then sell them to those who requested them from you for more than what you paid for them.