Implement membership payment system

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payment-gateway

hiii every body i make small app that used by this actors

- driver
- client
- vehicle

app will be used for vehicle services

i want to give client a service for charge his balance on my app with any method and he will use his balance to give payments to the vehicle

also driver has balance and he can call the service to use my app service as client

so i have to type of accounts

- clients accounts
- vehicle accounts

my question is how i make that :

- how to register the balance transactions for accounts types
- how to make transactions for payments from client account to vehicle account
- how to let clients or drivers to fund their balances over paybal and register this transaction
- how to calculate the current balances for clients and vehicles

if anyone has any UML for requirements please share it

thanks for sharing information ...

What I have tried:

make some google for collecting information and still need help from experts