Private loan false case

1. When the amount was credited to your bank account ie. Date
2. What was the mode of payment ie. by cheque or online transfer
3. If it was cheque, did you write the Bill details on the Pay-In Slip counterfoil when giving such cheque for collection to your Bank.It is the usual practice by traders to keep track of the cheques received and link them to the unpaid bills.
4. Have you issued a Bill to the Customer in his name with the cheque number noted there in or
5. Have you issued a credit bill in the name of the Customer and later squared it up when he issued cheque and such cheque was realised or received credit via online transfer from him.
6. If the amount creedited by the customer was through online transfer, how you have linked the amount to the goods sold. Did he inform by way of SMS/Whatsapp/E mail or orally informed.
7. How you have treated the dues from the Customer in your books from the date of sale shown him as as Debtor or how you have you treated the amount due from from the date of supply of goods and realisation of the cheque issued by him or credit to you account online.

If you have issued a receipt mentioning such cheque number and properly accounted for the goods sold, issue a strong reply notice demanding for production of such documents obtained and specifically inform the specific details of the goods sold with such date and receipt No...,  If there is a guarantee for such article explore the possibility of getting such evidence.

If you have the Invoice and amount is same against that invoice then no way they can do anything.

You have the receipt of goods ?

This is one side of your story, which is unbelievable.

Consult and engage a local prudent lawyer for appreciation of facts/ documents, professional advise and necessary proceeding.