Every customer gets a running ledger — paid, due and overdue — with reminders that get you paid.
The register works until it doesn’t: a payment goes unrecorded, an installment is forgotten, and a month later nobody agrees on the balance. TameerBook keeps each customer’s khata live, so the figure is never in doubt.
Set an installment plan, record part-payments as they come, and let the app send the reminder — in the language your customer reads — so chasing stops being your job.