Design and install an eCommerce platform to integrate with Sage

We use Sage Line 50 as our in house business operating system, it manages all our product records, prices, stock records, customer records, invoicing etc... We need to develop an online store which will integrate with Sage and allow both new and existing customers to log on and place orders etc... regardless of whether or not they have a credit account with us. We are concerned to try and achieve the the following functionality: 1. Clients in remote destinations to be charged a surcharge for delivery. 2. Shopping cart is to display all items ordered with facility to adjust quantities and remove items, when client clicks proceed to checkout items which are not available will come as a single list showing estimated availability dates and giving the customer 3 options: 1) Look for an alternative, 2) Send me this item when it is available, 3) Remove. 3. When the client clicks proceed again, (having chosen the option 2 for any items) then the system should take them through the completion of this part of the order. We need to make it clear that the order will not be despatched until all stock is available and carriage will be charged if the goods on this part of the order do not reach our carriage paid order level. 4. Having dealt with any items that are not available from stock, the system should then proceed to lead the client through the checkout procedure for the items which are in stock and available for immediate despatch. We need to make it clear that carriage will be charged if the goods on this part of the order do not reach our carriage paid order level if the client wants they need to have the option to wait for all goods to become available before any items are despatched, hence minimising any carriage liability. 5. Apart from all other usual features the following need to be included: a. Facility to generate a promotional discount code and email it to clients who qualify. b. Option to utilise a promotional discount code. c. Option to use a purchase order number d. Option to collect goods instead of have items delivered. e. Option to choose a timed delivery service at extra cost f. Option to chose or refuse a free gift with the delivery g. Option to donate to charity. 6. On completion of the order the website needs to generate an email providing the client with an invoice and order acknowledgement advising of estimated delivery date. 7. When the status of the order (or any part thereof) changes, the website needs to email the client with an update to inform them of the change(s). 8. The client must have the facility to log on to the website in order to track their orders, check on the status or progress of an order and alter or cancel an order. Administration We need the ability to log onto the website on behalf of any client and perform all of the above tasks on their behalf if necessary. In fact we propose to process all our sales, including telephone and written orders, via the website once it is launched. We also need the ability to edit all areas of the site, particularly product details, stock levels, prices and images.