Is it permissible to use shopping cards distributed by the employer that deduct an "administrative service" fee (2.5%) for every thousand dinars of the card's value, and allow purchases to be paid in installments over 18 months, knowing that some scholars have issued fatwas permitting it?

It is permissible for the issuing entity of the card to charge fees from the cardholder if these fees are equivalent to the actual value of the services provided for issuing the card. However, it is not permissible for it to take a percentage of the card's value. As for the entity that accepts the card (the merchant), it is not permissible for it to take any fees from the cardholder. If the merchant increases the price of the commodity or service for the cardholder, this falls under the suspicion of devising a trick to circumvent what is forbidden. The merchant's sale using the card must be at the same price as their cash sale.