EXCEL – Sum fixed range based in complex multiple criteria

I have 3 tables:

1. SALES
   Sale ID
   Provider Sell Count ID
   Client
   Provider
   Commission

2. COMMISSION PAYMENTS
   Sales Range
   Provider
   Amount Payed

3. COMMISSION AGENTS
   Client
   Agent Name
   Commission %

I need to calculate the amount that corresponds to each Commission Agent only from commissions that were already paid.

To do so i should use Sales Range in Commission Payments table and get all sales that are within that range and are from same provider in Sales table.

The Sales Range comes from the Provider Sell Count ID field in Sales Table.
That way i can have a record of which sales commissions have been payed for each provider.

Then i have to check for each of them who’s the client, check whose agent is that client from (based on the data on the third table) and multiply the commission amount by the commission percentage that corresponds to him.

I guess i should use some complex combination of MATCHs and INDEXs but couldnt get it to work, any ideas?

I hope i made myself clear.