Is it Islamically permissible to increase the installments for customers who are late in paying the price of IT devices in installments, by calculating an additional amount for each month of delay?

It is not permissible to increase installments or impose a late fee on the debtor, because that is usury (riba), which is forbidden. However, if the debtor is solvent and procrastinating, it is permissible to sue him to compel him to pay. A mortgage or a guarantor can be requested at the time of the sale contract to avoid procrastination.