Write SQL query to solve given problem: What is the company name of the customer who made the biggest amount of purchase in a single order before discount?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT T1.CompanyName FROM Customers AS T1 INNER JOIN Orders AS T2 ON T1.CustomerID = T2.CustomerID INNER JOIN `Order Details` AS T3 ON T2.OrderID = T3.OrderID WHERE T3.Discount = 0 GROUP BY T1.CompanyName ORDER BY SUM(T3.UnitPrice * T3.Quantity) DESC LIMIT 1