我认为我的功能可能是错误的

所以我不确定我到底做错了什么。我想我可能用错了函数。当我运行程序时，它不会询问用户想做什么，但如果我按下一个按钮，它会不断地将菜单记录到控制台，只需一次按下。我的国旗也可能有问题。对不起，我对此很陌生。

using System;
class Purse
{
    double check_balance(int p, int n, int d, int q)
    {
        return (p + 5 * n + 10 * d + 25 * q);
    }
    double insert(int p, int n, int d, int q)
    {
        return (p + 5 * n + 10 * d + 25 * q);
    }
    double remove(int p, int n, int d, int q)
    {
        return (p + 5 * n + 10 * d + 25 * q);
    }
    public static void Main()
    {
        int p = 0, n = 0, d = 0, q = 0, pChange = 0, nChange = 0, dChange = 0, qChange = 0;
        bool flag = true; // Flag
        char menu;
        Purse myBalance = new Purse(); 
        menu = Console.ReadKey().KeyChar;
        while (flag)
        {
            Console.WriteLine("What would you like to do?'n1. Check Balance'n2. Deposit'n3. Withdraw'n0. Close program");
            if (menu == 1)// Check the balance
            {
                myBalance.check_balance(p, n, d, q);
                continue;
            }
            else if (menu == 2)// Deposit
            {
                Console.WriteLine("Deposit how many pennies?");
                pChange = int.Parse(Console.ReadLine());
                p = p + pChange;
                Console.WriteLine("Deposit how many nickels?");
                nChange = int.Parse(Console.ReadLine());
                n = n + nChange;
                Console.WriteLine("Deposit how many dimes?");
                dChange = int.Parse(Console.ReadLine());
                d = d + dChange;
                Console.WriteLine("Deposit how many quarters?");
                qChange = int.Parse(Console.ReadLine());
                q = q + qChange;
                myBalance.insert(p, n, d, q);
                continue;
            }
            else if (menu == 3)// Withdraw
            {
                Console.WriteLine("Withdraw how many pennies?");
                pChange = int.Parse(Console.ReadLine());
                p = p - pChange;
                Console.WriteLine("Withdraw how many nickels?");
                nChange = int.Parse(Console.ReadLine());
                n = n - nChange;
                Console.WriteLine("withdraw how many dimes?");
                dChange = int.Parse(Console.ReadLine());
                d = d - dChange;
                Console.WriteLine("Withdraw how many quarters?");
                qChange = int.Parse(Console.ReadLine());
                q = q - qChange;
                myBalance.remove(p, n, d, q);
                continue;
            }
            else if(menu == 0)// close the menu
            {
                flag = false;
                break;
            }
            else// Improper input
            {
                Console.WriteLine("Please enter a menu number.");
                continue;
            }
        }
        Console.WriteLine("The program will now exit.");
    }
}