basically you should  connect company to customer then you should tell about intermeiaries used for the purpose & the transactions

first company has an database of customers with identification code and same identification code is also present on the credit card of the customer- every time he makes transaction an  transaction no is generated which either debit's the a/c or credit's, and all the process is stored in database, the important thing's will the following.

1)swift code on the card

2)transaction id

3)location

4)interest to charged based on the interest rate set up