c# - How to call base.base.method()?

Question

// Cannot change source code
class Base
{
    public virtual void Say()
    {
        Console.WriteLine("Called from Base.");
    }
}

// Cannot change source code
class Derived : Base
{
    public override void Say()
    {
        Console.WriteLine("Called from Derived.");
        base.Say();
    }
}

class SpecialDerived : Derived
{
    public override void Say()
    {
        Console.WriteLine("Called from Special Derived.");
        base.Say();
    }
}

class Program
{
    static void Main(string[] args)
    {
        SpecialDerived sd = new SpecialDerived();
        sd.Say();
    }
}

The result is:

Called from Special Derived.
Called from Derived. /* this is not expected */
Called from Base.

How can I rewrite SpecialDerived class so that middle class "Derived"'s method is not called?

UPDATE: The reason why I want to inherit from Derived instead of Base is Derived class contains a lot of other implementations. Since I can't do base.base.method() here, I guess the best way is to do the following?

// Cannot change source code

class Derived : Base
{
    public override void Say()
    {
        CustomSay();

        base.Say();
    }

    protected virtual void CustomSay()
    {
        Console.WriteLine("Called from Derived.");
    }
}

class SpecialDerived : Derived
{
    /*
    public override void Say()
    {
        Console.WriteLine("Called from Special Derived.");
        base.Say();
    }
    */

    protected override void CustomSay()
    {
        Console.WriteLine("Called from Special Derived.");
    }
}

Answer 1

Just want to add this here, since people still return to this question even after many time. Of course it's bad practice, but it's still possible (in principle) to do what author wants with:

class SpecialDerived : Derived
{
    public override void Say()
    {
        Console.WriteLine("Called from Special Derived.");
        var ptr = typeof(Base).GetMethod("Say").MethodHandle.GetFunctionPointer();            
        var baseSay = (Action)Activator.CreateInstance(typeof(Action), this, ptr);
        baseSay();            
    }
}