Excel expert

Hello I currently have over 300 customers and its been hard for me to follow up payments. I am looking to create an excel ledger that will help me to do the following • Identify Paid and unpaid invoices • Find out specific customers turnover whether it is been a week or a month • Be able to separate Paid invoices from the unpaid invoices • Some customers use different methods of payment so I would like to discriminate between each method • Different customers have different credit facilities and credit limit, I would like to be able for excel to notify me if they’ve reached credit limit or due time of payment • Some don’t pay completely so I would like an option where excel notifies me that there’s a balance to pay • Some customers give me return goods which I need to deduct from their total of the current invoice so I would like an option for that too • More information- I need to be able to distinguish because some outlets have 5-6 branches I don’t want a messy excel ledger • Each customer can take more than one invoice so I want to be able to distinguish what payment is for which invoice number