private void SearchByAccountNumber_Click(object sender, EventArgs e)
        {
            int number = 0;

            if (AccountNumber.Text == String.Empty || AccountNumber.Text.Length != 5 || !Int32.TryParse(AccountNumber.Text, out number))
            {
                ValidationMessage("You didn't enter the account number.");
                return;
            }

            try
            {
                DisableControls();

                UserDto userDto = _client.GetByAccountNumber(number);
                if (userDto == null)
                {
                    MessageBox.Show("Client account not found");
                    EnableControls();
                    return;
                }
                _userDto = userDto;

                UserName.Text         = _userDto.Name;
                Balance.Text          = _userDto.Balance.ToString();
                ValidationDate.Text   = _userDto.ValidTillDate.ToString("dd/MM/yyyy");
                Phone.Text            = _userDto.Phone;
                Notes.Text            = _userDto.Notes;
                ModificationDate.Text = _userDto.ModificationDate.ToString("dd/MM/yyyy");
                MonthlyFeeDate.Text   = _userDto.MonthlyFeeDate.ToString("dd/MM/yyyy");

                SaveChanges.Enabled = true;
            }
            catch (FaultException ex)
            {
                ErrorMessage(ex.Message);
            }
            catch (EndpointNotFoundException ex)
            {
                ErrorMessage(ex.Message);
            }
            finally
            {
                EnableControls();
            }
        }