private void ClearBtn_Click(object sender, EventArgs e)
 {
     if (CcNumber.Visible)
     {
         CcNumber.Clear();
     }
     else
     {
         PinNumber.Clear();
     }
 }
 private void CancelBtn_Click(object sender, EventArgs e)
 {
     PinNumber.Clear();
     CcNumber.Clear();
     RequestCcNumber();
 }