[Your Name, & Address here]
[Recipient Name & address here]
We have your promissory note dated [date of note] in the amount of $[original amount].
We would like to inform you that you have defaulted on this note to pay the following [amounts/installments]:
– [list past due payments here] –
So, we demand payment of [total due amount] from you.
If we do not receive our payment by [payment deadline], we will be forced to recover this amount at your expense, as mentioned in the promissory note.
Encl: [Enclosures List here]