Make changes to OpenCart, multi vendor -- 2

1) Members can post product must be able to record the cost of sending their products according to the city (the selected country, state and city), product by product. Comment : is under product you have data tab, please provide next tab as shipping tab let him select which country, state, city and Shipping price. if he trying to do same city twice error should pop saying you have already enetered. 2) When a buyer sees the product (detail of product) will select the city they want to recive and the system will display the price of shipping to that city. Comment : seleccione el país / estado / ciudad usando ajax para que la página no se actualizará, 3) At the stage of the shopping cart, should appear shipping cost depending on the city you selected alla buyer. (If not defined the shipping cost for that city, we request contact details to contact with the seller). comment : you will give a delete option and show that you have to delete this product as , this product cannot be delivered to your city, when clicking delete -- a pop which says contact seller directly -- they the form contains name, email id and phone number which goes to seller 4) The shipping cost is defined for each product, so if the buyer purchases more than one, the cost will be: The shipping cost to the city multiplied by the number of items purchased from this reference. Site: [login to view URL]