Unity2D ボールを壁で跳ね返す

前提・実現したいこと

ボールを壁で跳ね返したい

該当のソースコード

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class MouseClickPoint : MonoBehaviour
{
    public static Vector2 mousePosition;
    private Mesh mesh;
    public Material material;
    private bool meshDrawed;
    public static Vector2 bMousePos = new Vector2(1000,0);
    public static bool goAllowedBall;
    void Start()
    {
        mesh = new Mesh();
        mesh.vertices = new Vector3[]
        {
            new Vector3(0,0,0),
            new Vector3(0.25f,0,0),
            new Vector3(0,0.25f,0),
            new Vector3(0.25f,0.25f,0),
        };

        mesh.uv = new Vector2[]
        {
            new Vector2(0,0),
            new Vector2(0,1),
            new Vector2(1,0),
            new Vector2(1,1),
        };
        mesh.triangles = new int[]
        {
            0,1,2,
            1,3,2,
        };
        mesh.RecalculateNormals();
        mesh.RecalculateBounds();
    }

    void Update()
    {
        if (Game.gameStarted)
        {
            var pos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
            if (pos.x > 2.4f)
            {
                mousePosition = new Vector2(2.28f, pos.y);
            }
            if (pos.x < -2.5f)
            {
                mousePosition = new Vector2(-2.5f, pos.y);
            }
            if (pos.x < 2.4f && pos.x > -2.5f)
            {
                if (Input.GetMouseButtonDown(0))
                {
                    meshDrawed = true;
                    bMousePos = new Vector2(mousePosition.x, mousePosition.y);
                    goAllowedBall = true;
                }
                mousePosition = new Vector2(pos.x, pos.y);
            }
        }
        if (meshDrawed)
        {
            Graphics.DrawMesh(mesh, bMousePos, Quaternion.identity, material, 0);
        }
    } 
}

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;
public class BallMove : MonoBehaviour
{
    //速度
    public Vector2 velocity = new Vector2(0.1f, 0f);
    private Vector2 ballPosition;
    private float fVelocity = 0.1f;
    private float fAngle;
    public GameObject Ball;
    //二点間の角度を求める
    float ExposeDegree(Vector2 basePos,Vector2 targetPos)
    {
        //基準の位置から目標の位置までのベクトルを求める
        Vector2 dif = targetPos - basePos;
        //ラジアン
        float radian = Mathf.Atan2(dif.y, dif.x);
        //角度
        float degree = radian * Mathf.Rad2Deg;
        return degree;
    }
    float ExposeAngle(float num)
    {
        float angle = (num * 3.14f) / 180;
        return angle;
    }
    private void Start()
    {
        ballPosition = Ball.transform.position;
    }
    private void Update()
    {
        if (MouseClickPoint.goAllowedBall)
        {
            CalculateVelocity();
            ballPosition += velocity;
            ReflectToWall();
            Ball.transform.position = ballPosition;
        }
    }
    private void CalculateVelocity()
    {
        Vector2 firstPosition = new Vector2(0, 0);
        Vector2 targetPosition = MouseClickPoint.bMousePos;
        float degree = ExposeDegree(firstPosition, targetPosition);
        fAngle = ExposeAngle(degree);
        velocity.x = fVelocity * Mathf.Cos(fAngle);
        velocity.y = fVelocity * Mathf.Sin(fAngle);
    }
    private void ReflectToWall()
    {
        if(ballPosition.x > 2.4f)
        {
            ballPosition.x = 2.4f;
            velocity.x = -velocity.x;
        }
    }
}

試したこと

ReflectToWall()でボールが壁で跳ね返るようにしたかったのですが、どうやってもＹ方向に直線に進むだけです。どのサイトを見ても、速度をマイナスに反転させれば壁で跳ね返ると書いてあるのにまったく成功しません。
基本的なことなのに出来ず、完全にお手上げです。どうしたら壁でボールを反射させられますか？
回答お願いします。