OCP.cs

using System;

namespace IMJunior
{
    class Program
    {
        static void Main(string[] args)
        {
            PaymentBase paymentBase = new PaymentBase();
            OrderForm orderForm = new OrderForm(paymentBase);
            PaymentHandler paymentHandler = new PaymentHandler(paymentBase);
            string systemId;

            orderForm.ShowForm();
            systemId = orderForm.GetUserInput();

            paymentHandler.SetConnection(systemId);
            paymentHandler.ShowPaymentResult(systemId);
        }
    }

    public class OrderForm
    {
        private List<IPaymantSystem> _paymentSystemList;

        public OrderForm(PaymentBase paymentBase)
        {
            _paymentSystemList = new List<IPaymantSystem>();

            paymentBase.GetPaymentList(_paymentSystemList);
            
        }
        public void ShowForm()
        {
            Console.WriteLine("Мы принимаем: ");

            for (int i = 0; i < _paymentSystemList.Count; i++) 
            {
                Console.WriteLine($"{_paymentSystemList[i].GetPaymentName()}");
            }
        }

        public string GetUserInput() 
        {
            Console.WriteLine("Какой системой вы хотите совершить оплату?");
            return Console.ReadLine();
        }
    }

    public class PaymentHandler
    {
        private List<IPaymantSystem> _paymentSystemList;

        public PaymentHandler(PaymentBase paymentBase) 
        {
            _paymentSystemList = new List<IPaymantSystem>();

            paymentBase.GetPaymentList(_paymentSystemList);
        }

        public void SetConnection(string systemId) 
        {
            foreach (var item in _paymentSystemList)
            {
                if (item.GetPaymentName() == systemId)
                {
                    item.SetConnection();
                    break;
                }
            }
        }

        public void ShowPaymentResult(string systemId)
        {
            Console.WriteLine($"Вы оплатили с помощью {systemId}");

            foreach (var item in _paymentSystemList) 
            {
                if (item.GetPaymentName() == systemId)
                {
                    ShowPaymentStatus(systemId);
                    break;
                }
            }
        }

        public void ShowPaymentStatus(string name)
        {
            Console.WriteLine($"Проверка платежа через {name}...");
            Console.WriteLine("Оплата прошла успешно!");
        }
    }

    public class PaymentBase 
    {
        private List<IPaymantSystem> _paymentSystemList;

        public PaymentBase()
        {
            _paymentSystemList = new List<IPaymantSystem>();

            _paymentSystemList.Add(new Webmoney());
            _paymentSystemList.Add(new QIWI());
            _paymentSystemList.Add(new Card());
        }

        public void GetPaymentList(List<IPaymantSystem> paymantSystems) 
        {
            foreach (var intem in _paymentSystemList) 
            { 
                paymantSystems.Add(intem);
            }
        }
    }

    public interface IPaymantSystem
    {
        public string GetPaymentName();
        public void SetConnection();
    }

    public class Card : IPaymantSystem
    {
        private string _name = "Card";
        public string GetPaymentName()
        {
            return _name;
        }

        public void SetConnection()
        {
            Console.WriteLine($"Вызов API банка эмитера карты {_name}...");
        }
    }

    public class QIWI : IPaymantSystem
    {
        private string _name = "QIWI";

        public void SetConnection()
        {
            Console.WriteLine($"Перевод на страницу {_name}...");
        }

        public string GetPaymentName()
        {
            return _name;
        }
    }

    public class Webmoney : IPaymantSystem
    {
        private string _name = "Webmoney";
        public string GetPaymentName()
        {
            return _name;
        }

        public void SetConnection()
        {
            Console.WriteLine($"Вызов API {_name}...");
        }
    }
}