Ai Movement Problems

Hello!
I am trying to script a very simple Ai for my game.
This Code is just for moving my Ai in four DIrections which where randomly chosen.
So very basic.
But when I try this script on a gameobject in Unity it just flows away and ist not working at all.
I set many times that the Y Position cant be changed but the script gives a S***.
I dont know what do to any more so I would apreciate some help.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class Ai : MonoBehaviour
6. {
7.     float direction;
8.     float positionx;
9.     float positiony;
10.     float positionz;
11.  
12.     public float timeLeft = 4.0f;
13.  
14.     Vector3 moveDirection;
15.  
16.     public Transform enemy;
17.  
18.     void Start()
19.     {
20.         direction = Random.value;
21.     }
22.  
23.     void Update()
24.     {
25.         timeLeft -= Time.deltaTime;
26.  
27.         CharacterController controller = GetComponent<CharacterController>();
28.  
29.         positionx = (enemy.transform.position.x);
30.         positiony = (2.77f);
31.         positionz = (enemy.transform.position.z);
32.  
33.         if(direction < 0.25f)
34.         {
35.             while(timeLeft > 0)
36.             {
37.                 transform.Rotate(0, 180, 0);
38.                 moveDirection = new Vector3(positionx, 2.77f, 0.25f);
39.                 controller.Move(moveDirection * Time.deltaTime);
40.                 break;
41.             }
42.             if (timeLeft < 0)
43.             {
44.                 direction = Random.value;
45.                 timeLeft = 4.0f;
46.             }
47.         }
48.         if(direction > 0.25f && direction < 0.5f)
49.         {
50.             while(timeLeft > 0)
51.             {
52.                 transform.Rotate(0, 90, 0);
53.                 moveDirection = new Vector3(0.25f, 2.77f, positionz);
54.                 controller.Move(moveDirection * Time.deltaTime);
55.                 break;
56.             }
57.             if (timeLeft < 0)
58.             {
59.                 direction = Random.value;
60.                 timeLeft = 4.0f;
61.             }
62.         }
63.         if(direction > 0.5f && direction < 0.75f)
64.         {
65.             while(timeLeft > 0)
66.             {
67.                 transform.Rotate(0, 270, 0);
68.                 moveDirection = -new Vector3(0.25f, 2.77f, positionz);
69.                 controller.Move(moveDirection * Time.deltaTime);
70.                 break;
71.             }
72.             if (timeLeft < 0)
73.             {
74.                 direction = Random.value;
75.                 timeLeft = 4.0f;
76.             }
77.         }
78.         if(direction > 0.75f && direction < 1.1f)
79.         {
80.             while(timeLeft > 0)
81.             {
82.                 transform.Rotate(0, 360, 0);
83.                 moveDirection = -new Vector3(positionx, 2.77f, 0.25f);
84.                 controller.Move(moveDirection * Time.deltaTime);
85.                 break;
86.             }
87.             if (timeLeft < 0)
88.             {
89.                 direction = Random.value;
90.                 timeLeft = 4.0f;
91.             }
92.         }
93.     }
94. }

 

I solved the Problem with the Y Position by my own but i still dont know why my gameobject rotates.

 

Lines 52, 67 and 82 all change the rotation.

 

thanks