How Do I Activate The Switch Statement

OK I have been at this for hours, I can receive the characters into Unity through the serial port from the Arduino but HOW do I get them to activate my switch statement at the bottom of the script.

 // Update is called once per frame
     void Update () {
         /*string dataFromArduinoString = sp.ReadLine ();
         int dFAI = int.Parse (dataFromArduinoString);
         print (dFAI);
         DirectionArrow (dFAI);*/
 
         try
         {
             //DirectionArrow(sp.ReadByte());
             //print(sp.ReadByte());
             /*string dataFromArduinoString = sp.ReadLine ();
             int dFAI = int.Parse (dataFromArduinoString);
             print (dFAI);
             DirectionArrow (dFAI);*/
             string message3 = sp.ReadLine(); //get the message...
             if(message3 == ""); //if its empty stop right here
             print(message3);
             DirectionArrow (message3);
             ///////////
             /// CALL  THIS TO THE SWITCH CASE BOTTOM OF SCRIPT.... HOW DO I DO THAT??
             ///////////
         }
         catch (System.Exception) {
 
         }
             //print("BytesToRead" +sp.BytesToRead);
             message2 = sp.ReadLine();
             
         string message = sp.ReadLine(); //get the message...
         if(message == "") return; //if its empty stop right here
         // parse the input to a float and normalize it (range 0..1) (we could do this already in the Arduino)
 
         float input =  1 -  float.Parse (message) / 100f;
         // set the slider to the value
         float oldValue = slider.value; // -------- this is new
         slider.value = input;
 
         // after the slider is updated, we can check for the other things for example play sounds:
 
         if (source.isPlaying) return; // if we are playing a sound stop here
 
         // else check if we need to play a sound and do it
         if (slider.value > 0.9f && oldValue <= 0.9f) // ---------this has changed
             source.PlayOneShot (BrightnessAudioClips [Random.Range (0, BrightnessAudioClips.Length)]);
 
         else if (slider.value < 0.15f && oldValue >= 0.15f) //----------this has changed
             source.PlayOneShot (DarknessAudioClips [Random.Range (0, DarknessAudioClips.Length)]);
         
 
     }
 
 
 void DirectionArrow(string buttonStatus)
     {
         
     switch (buttonStatus)
     {
         //OFF Buttons  States
         case "O":
             //deactivate Left Direction Arrow
             SystemGuidanceManagerScript WAOff = FindObjectOfType<SystemGuidanceManagerScript>();
             WAOff.WestArrowOff ();
 
             SystemGuidanceManagerScript EAOff = FindObjectOfType<SystemGuidanceManagerScript>();
             EAOff.EastArrowOff();
 
             SystemGuidanceManagerScript SFXOff = FindObjectOfType<SystemGuidanceManagerScript>();
             SFXOff.TopIndicatorOff();
 
             SystemGuidanceManagerScript BGSOff = FindObjectOfType<SystemGuidanceManagerScript>();
             BGSOff.BarLEDsSounderOff();
             break;
         //LEFT BUTTON ON STATE
         case "W":
             //Activate Left Direction Arrow Indicator
             SystemGuidanceManagerScript WAOn = FindObjectOfType<SystemGuidanceManagerScript>();
             WAOn.WestArrow();
 
             SystemGuidanceManagerScript WBSOn = FindObjectOfType<SystemGuidanceManagerScript>();
             WBSOn.BarLEDsSounderOn();
             break;
         //RIGHT BUTTON ON STATE
         case "E":
             //Activate Right Direction Arrow Indicator
             SystemGuidanceManagerScript EAOn = FindObjectOfType<SystemGuidanceManagerScript> ();
             EAOn.EastArrow ();
 
             SystemGuidanceManagerScript EBSOn = FindObjectOfType<SystemGuidanceManagerScript>();
             EBSOn.BarLEDsSounderOn();
             break;
     }
             
     }