Is it permissible not to pay the additional service fees requested by the application, which amount to 5% of the order price, in addition to the price of the order and delivery, even though it does not provide any additional service?

"It is not clear why a service fee would be imposed after the price of the order and delivery have been paid, unless it is for the use of the application. If the application owner requests these fees in exchange for making it available for use, then they are considered as rent (ujra) or the price of a benefit. If the price of the order is known, then the requested percentage (rent) is also known. A rental agreement (ijara) is a binding contract. Therefore, if the enquirer knew in advance that the application imposes these fees, he is obligated to pay them and is not permitted to refuse."