API Development

I need someone to help integrate my current financial system (quickbooks) with my Joomla website and Virtumart so that when customers order from the website it updates stock levels in quickbooks and the website. I also need someone to help develop an API. We are a distributor and the current distribution of stock for our carrier grade customers is very manual. They send an order with the units required, address etc, we then send them the invoice with the MAC address of the device, serial number, connote number etc. I want the API to be able to receive their order and then for our system to automatically send them the invoice and order status with all the necessary information on the order form that they require. There would need to be integration between our carriers purchasing system and ours to make this work I would assume. I would require someone with experience with this level of development. Thanks