Build a website with customer accounts and payment gateway and transaction facility.

We are looking for someone who is an expert in building websites preferably joomla website. 1) We need all our customers to have online account and to have facility to pay for different types of comercial plans. 2) There should be a messaging system from where customers can contact us. and provide some confidential data. 3) Customer executives should be able to contact customers by sending messages directly to their account. 4) Customers from all across world should be able to sign up and create accounts. More details will be provided later.