Loans: How to apply late fees, interest, and principle amounts to respective dates.

Hello,

I am having difficulty in understanding how formula's work for a loan amortization. I loaned some money in the form of a Promissory Note. The loan is now in default and I am trying to create a spreadsheet that shows the details and respective balance's of the Note. The Note dictates a 3 year term, 7% compounded APR, a fixed scheduled payment amount and late fees of 1% compounded monthly. The late fees apply if it is not paid by the due date and/or the monthly amount is not paid in full.

I have searched through the posts to find assistance in doing this on my own to no avail. I have tried to self-learn the fx's of IPMNT, IF, (many others) and what/how to use the formula so that the cells recognize when a payment is late, and if/how much late fee's to apply. I also need the cells to recognize the amount paid (regardless of when) and to apply the payments in a specific priority. The order of priority is:

#1 Late fee's
#2 Interest
#3 Principle

Once those sum's are calculated, I need to have the respective total amounts shown in each respective cell that is in the Note Summary area. I have worked on this for weeks; now, after countless attempts and restarts, I have learned much however, I must confess that I may have the computing sums, balance, and applied payments completely wrong at this point.

I have attached a file that has all the details; the file does not have the formulas needed so that I can provide the ending balance YTD.

Any help would be very much appreciated.