private void btnUnsubscribe_Click(object sender, EventArgs e)
        {
            if (chkEmail.Checked)
            {
                string email = txtEmail.Text;
                eCustomer = new SendViaEmail(email);
                SendViaEmail removeItem = null;

                foreach (SendViaEmail item in CustomersList.EmailCustomers)
                {
                    // MessageBox.Show(string.Format("{0}",string.Compare(item.ToString(),pCustomer.ToString())));

                    if (string.Compare(item.ToString(), eCustomer.ToString()) == 0)
                    {
                        item.UnSubscribe(publisher);
                        removeItem = item;

                        MessageBox.Show(String.Format("Email {0} UnSubscribed", email));
                    }
                }
                CustomersList.EmailCustomers.Remove(removeItem);
            }

            if (chkMobile.Checked)
            {
                string mobile = txtMobile.Text;
                pCustomer = new SendViaMobile(mobile);
                SendViaMobile removeItem = null;


                foreach (SendViaMobile item in CustomersList.MobileCustomers)
                {
                    // MessageBox.Show(string.Format("{0}",string.Compare(item.ToString(),pCustomer.ToString())));

                    if (string.Compare(item.ToString(), pCustomer.ToString()) == 0)
                    {
                        item.UnSubscribe(publisher);
                        removeItem = item;
                        MessageBox.Show(String.Format("Mobile {0} UnSubscribed", mobile));
                    }
                }
                CustomersList.MobileCustomers.Remove(removeItem);
            }
        }
        private void btnSubscribe_Click(object sender, EventArgs e)
        {
            //Subscribe email
            if (chkEmail.Checked && VerifyEmail())
            {
                string email = txtEmail.Text;
                eCustomer = new SendViaEmail(email);

                //validate duplicate
                if (!(IsDuplicate <SendViaEmail>(eCustomer)))
                {
                    eCustomer.Subscribe(publisher);
                    CustomersList.EmailCustomers.Add(eCustomer);
                    MessageBox.Show(String.Format("Your email {0} Subscribed successfully", email));
                }
                else
                {
                    MessageBox.Show("email already subscribed");
                }
            }

            //subscribe mobile
            if (chkMobile.Checked && VerifyMobile())
            {
                string mobile = txtMobile.Text;
                pCustomer = new SendViaMobile(mobile);
                //validate duplicate

                if (!(IsDuplicate <SendViaMobile>(pCustomer)))
                {
                    pCustomer.Subscribe(publisher);
                    CustomersList.MobileCustomers.Add(pCustomer);
                    MessageBox.Show(String.Format("Your mobile {0} Subscribed successfully", mobile));
                }
                else
                {
                    MessageBox.Show("Mobile already subscribed");
                }
            }
        }