Loan Amortization Spreadsheet

I am looking for an experienced freelancer to create a loan amortization spreadsheet for business loans. The spreadsheet should be able to calculate monthly payments and prepare an amortization schedule based on the input of different criteria (maturity date, installment payment amount, deferred payment period, other additions to loan balance such as collection costs/attorneys fees, etc.). I've currently got a spreadsheet that is very close to what I want, but it seems to have some errors that are affecting calculations that I can't figure out. I'm not sure if it will be easier to fix the existing spreadsheet or start from scratch, but at least the current doc will let you see what I'm looking for. Thanks!