//this method gets called to add items in the invoice
public void Bill(string itemName)
{
Invoice invoice = new Invoice(new InvoiceIndustry().createInvoiceType(itemName));
Session["selectedItem"] = itemName;
invoice.AddFood((List <Item>)Session["items"]);
invoice.ChargeInItem(Get_Service(), (List <Item>)Session["items"], itemName);
Custom_GridView(itemName);
}
