What is the ruling on dealing with a company that allows the purchase of products with a credit limit and deducts the price of the item while calculating interest based on the installment period and a late payment penalty, and what is the ruling on dealing with merchants in their special program?

It is not permissible to deal with a credit limit if the company pays the value of purchases on behalf of the customer and then collects a higher amount from him, because it is a loan with usurious interest. Furthermore, the late payment fee imposed by the company is the forbidden usury of the pre-Islamic era (Jahiliyyah). This transaction is not permissible even if payments are made regularly, due to the usury involved. As for the ruling on dealing with merchants using their special program, it depends on how similar it is to the company's previously mentioned program.