private void accept_Click(object sender, EventArgs e) { int op = Convert.ToInt32(opInputText.Text); try { RefundResponse response = POS.Instance.Refund(op); if (response.Success) { MessageBox.Show(response.ToString(), "Refund Success."); this.Close(); } } catch (TransbankException a) { MessageBox.Show(a.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); } }