بسم اللہ الرحمٰن الرحیم

:الجواب وباللہ التوفیق

First, one should avoid borrowing interest-based loan from the bank as much as possible. But if in dire need of money, it is necessary to become thoughtful and exercise every effort to pay back each installment before its specified time. 

Regarding the interest that has become due in case of non-payment of installments, following procedure can be adopted for its payout:

If the loan is taken from the same bank where you already have a savings account, then the interest earned on your deposited money can be included in the payable interest on the loan. In this case, the intention should be that “the interest amount is being returned to the original owner".

فی الدر المختار: ’’شمل الرد حكما لما في جامع الفصولين : وضع المغصوب بين يدي مالكه برئ ، وإن لم يوجد حقيقة القبض ‘‘ (ردالمحتار: کتاب الغصب)

لان سبیل الکسب الخبیث التصدق اذا تعذرا الرد علی صاحبہ ۔(کتاب النوازل:۳۵۲)

فقط واللہ اعلم بالصواب