Dear Sir/ Madam,
This is to inform you that I have been unable to make payments on time for the past [insert number of months] months due to [insert reason for late payments]. My earlier payments have always been on time. I have been successful in recovering from [insert reason for late payments] and am now capable of paying back the debt.
My account with you has been delinquent for the past [insert number of months] and I am more than willing to repay immediately. I will be paying for the next consecutive three months as proof of my ability to repay my obligation. This is an earnest request to you to consider re-aging my accounts if I fulfill all the eligibility criteria. I would be obliged if you consider my request.
Please get back to me for any further information that I might be able to furnish you with. Thank you for your cooperation.