HighScore - Timer

Hello, Im trying to make a level completion timer for my game. What Im trying to do is make a string show the time of the level completion, but, the problem is that saving a high score isn't working. It keeps being 00:00:00. I want the shortest time to be the high score.

This is my whole script :

 var highScore : String;
 var score : String;
 
 var guiSkin : GUISkin;
 
 var minutes : float;
 var seconds : float;
 var miliseconds : float;
 
 var levelComplete : boolean = false;
 
 function Awake()
 {
     
 }
 
 function Update()
 {
 
     score = minutes.ToString("00") + ":" + seconds.ToString("00") + ":" + miliseconds.ToString("100");
     highScore = PlayerPrefs.GetFloat("Minutes").ToString("00") + ":" + PlayerPrefs.GetFloat("Seconds").ToString("00") + ":" + PlayerPrefs.GetFloat("Miliseconds").ToString("00");
     PlayerPrefs.SetString("HighScore", highScore);
     miliseconds += 60 * Time.deltaTime;
 
     if(miliseconds > 60)
     {
         miliseconds = 0;
         seconds += 1;
     }
     
     if(seconds > 60)
     {
         minutes += 1;
         sesconds = 0;
     }
 }
     
 function OnGUI()
 {
     if(levelComplete == true)
     {
         if(seconds < PlayerPrefs.GetFloat("Seconds"))
         {
             PlayerPrefs.SetFloat("Seconds", seconds);
         }
 
         if(miliseconds < PlayerPrefs.GetFloat("Miliseconds"))
         {
             PlayerPrefs.SetFloat("Miliseconds", miliseconds);
         }
 
         if(minutes < PlayerPrefs.GetFloat("Minutes"))
         {
             PlayerPrefs.SetFloat("Minutes",minutes);
         }
     }
 }

Thank you for your time.

Edit :

I forgot to add another script of mine, this one:

 var scoreBoard : ScoreBoard;
 
 function Awake()
 {
     scoreBoard = GameObject.FindWithTag("Player").GetComponent(ScoreBoard);
 }
 
 function OnCollisionEnter (col : Collision)
 {
     if(col.collider.gameObject.tag == "Player")
     {
         scoreBoard.levelComplete = true;
         Time.timeScale = 0;
     }
 }