C#: Force Compiler error on use of myObj.ToString()

using System;

public class Foo
{
    public int ID = 123;
    public string Name = "SomeName";

    private string ToString() { return null; }
}

public class MyClass
{
    public static void Main()
    {
    	Foo myObj = new Foo();
    	WL("I want this to be a compiler error: {0}", myObj.ToString());
    	RL();
    }

    #region Helper methods

    private static void WL(object text, params object[] args)
    {
    	Console.WriteLine(text.ToString(), args);
    }

    private static void RL()
    {
    	Console.ReadLine();
    }

    #endregion
}

[Obsolete("Use the XYZ properties instead of .ToString() on Foobar", true)]

[Obsolete("dont' use", true)]
    public override string ToString()
    {
        throw new Exception("don't use");
    }

Foo myObj = new Foo();

        Console.WriteLine(myObj);

public string CreateItemUrl(int itemId)
{
   return string.Format("someurl.aspx?id={0}", itemId);
}

CreateItemUrl(myObj.Id);

string theUrl = string.Format("someurl.aspx?id={0}", myObj);

public new void ToString() { }