moving on Y problem

Unity Engine
1

Hi. I am using the CNcontroller plugin, which it comes with the prefabs and the scripts i need. Everything works fine, i have just a problem. Sometimes, the player is moving on the Y. I don’t want that and it shouldn’t do that. What is to do ?
Here’s the script i am using. It comes as an example with the cncontroller prefab. I found it very suitable to my project so i kept it.

using System;
using UnityEngine;
using System.Collections;

[RequireComponent(typeof(CharacterController))]
public class Controller3DExample : MonoBehaviour
{
    public const float ROTATE_SPEED = 15f;

    public float movementSpeed = 5f;

    public CNAbstractController MovementJoystick;

    private CharacterController _characterController;
    private Transform _mainCameraTransform;
    private Transform _transformCache;
    private Transform _playerTransform;

    void Start()
    {
        // You can also move the character with an event system
        // You MUST CHOOSE one method and use ONLY ONE a frame
        // If you wan't the event based control, uncomment this line
        // MovementJoystick.JoystickMovedEvent += MoveWithEvent;

        _characterController = GetComponent<CharacterController>();
        _mainCameraTransform = Camera.main.GetComponent<Transform>();
        _transformCache = GetComponent<Transform>();
        _playerTransform = _transformCache.FindChild("Cocoon");
    }

    // Update is called once per frame
    void Update()
    {
        var movement = new Vector3(
            MovementJoystick.GetAxis("Horizontal"),
            0f,
            MovementJoystick.GetAxis("Vertical"));

        CommonMovementMethod(movement);
    }

    private void MoveWithEvent(Vector3 inputMovement)
    {
        var movement = new Vector3(
            inputMovement.x,
            0f,
            inputMovement.y);

        CommonMovementMethod(movement);
    }

    private void CommonMovementMethod(Vector3 movement)
    {
        movement = _mainCameraTransform.TransformDirection(movement);
        movement.y = 0f;
        movement.Normalize();

        FaceDirection(movement);
        _characterController.Move(movement * movementSpeed * Time.deltaTime);
    }

    public void FaceDirection(Vector3 direction)
    {
        StopCoroutine("RotateCoroutine");
        StartCoroutine("RotateCoroutine", direction);
    }

    IEnumerator RotateCoroutine(Vector3 direction)
    {
        if (direction == Vector3.zero) yield break;

        Quaternion lookRotation = Quaternion.LookRotation(direction);
        do
        {
            _playerTransform.rotation = Quaternion.Lerp(_playerTransform.rotation, lookRotation, Time.deltaTime * ROTATE_SPEED);
            yield return null;
        }
        while ((direction - _playerTransform.forward).sqrMagnitude > 5f);
    }

}

What to do ? As i said, it only happens sometime. In general, it happens when i want to walk in my front and my right … (diagonal). I am working at a first person view project and i don;t want my player to move on y. Ha ha ha, is so trolling when the player kicks the roof :))

2

same help, please ? I ve been trying everything