Full-featured e-commerce web site building

We are looking for professional and skilled web developing company in order to build full featured e-commerce web site (a new online store) using one of the next platforms: Prestashop, Magento or Joomla. Technical requirements - We have two suppliers (PixmaniaPro and ETC-UK) and it is necessary to upload two different CSV files which contain a large number of products. Products must be sorted by categories, manufactories, etc. CSV files are available to be tested. - We must be able to update product database with new CSV files by ourselves without a need to engage anyone to do it instead of us. - In Admin control panel should be set up margins between wholesale and retail prices for different product categories. We also must be able to amend this margin as needed. - Customers must be able to search products by name, compare their features, prices and perform others operations that are usual for good design e-commerce web site but logical for navigation. - PayPal payment option must be integrated along with a payment form by popular bank cards (Visa, MasterCard, Maestro, American Express, etc.). Google checkout also must be included. - SEO and web promotion. - Possibility to enter promotional codes for discounted prices. - Online contact form. We have hosting package at [login to view URL] server but we have already experienced technical problems with installation required software. In the case that you were not able to complete this job at our server because of any technical problem you would be asked to install software on another server which you are experienced with. We prefer it to be a server located in UK. In that case our web address should be redirected to the server where online store is installed. The job should be done within two weeks.