Diwali is when the credit book stops being manageable

Most kirana stores extend credit, and most manage it in pen. For eleven months of the year this is fine. The book is small enough to scan, and the owner carries the exceptions in memory.

What festival season does

Volume rises, new customers appear, and the amounts get larger. The book is now three pages deep per letter and the person at the counter cannot check a balance while a queue is forming. So they stop checking. Credit is extended on impression rather than on the number.

The consequence arrives six weeks later, when settlement is slower than usual and the shop has less working capital at exactly the point it needs to restock.

What a system has to do to be used here

Show the balance on the screen the biller is already looking at. Anything that requires leaving the sale will not be done during a rush, which is precisely when it matters.

Accept a part-payment in two taps. Customers pay something on account constantly; if that needs an accounting entry it will be recorded in the book instead, and the two records will diverge.

The reminder question

A message with the balance is usually easier for both sides than a phone call — it is checkable, unembarrassing, and can be ignored without a confrontation. But a shop will abandon any tool that makes a good customer feel chased, so the timing has to be the owner's decision, not a default schedule.