The Area being Modelled is :-
A Database for Medical Laboratories with Payments

Roberto says :-   
OK, so basically this is what I have right now. please excuse the language -literally :) but spanish is not hard to crack.

Paciente is Client, Resultado is Test Result, and Empresa is Company - oh by the way, this DB is to report tests results for a medical laboratory.

I use this currently to do reports BUT, I want to add billing capabilities.

By this I mean that I want at the end to show how much the Company has to pay for the tests.

I know this doesn�t obey almost ANY law of data normalization so I guess we could start from there.

The Resultado table holds all the variables of ALL the different tests that are performed in the lab;

note not all clients have all the test taken.