Calculation for default & delinquent payment

I am looking for a formula that calculates the monthly default & delinquent amount for each customer.

A customer would be a delinquent customer if no payment received from the last two months. If three months elapsed without payment customer becomes the default.

In the attached spreadsheet, column O to column T shows the monthly repayment amount & outstanding balance by month. Column AE to AJ represents the payments received by the month, and column AL to AS shows the default & delinquent payment calculation.

E.g., the customer in line 8 is missing July, Aug & Sept payment; therefore, as per the criteria customer is in delinquent status in September i.e., in cell AN8, the formula should return the outstanding loan balance from the last payment month (in this case June).

Similarly, if the same customer hasn't paid in the 3rd month, it becomes the default in October. The formula should return the value from the outstanding loan balance. Also, once the customer is reported as a default/ delinquent customer, nothing should be populated in the coming months until the customer starts paying back.

Hope this make sense.....