I'm guessing that you want to add the new values into the hashref that is $row, not to the arrayref that is $data?

If so then you can use slice assignment (untested):

     my %new_row_data = (new_name => $name, new_ad1 => $ad1, new_City 
+=> $town, new_z_code => $zcode);
     @$row{keys %new_row_data} = values %new_row_data;
[download]

You could also loop over the keys of %new_row_data and add each key/value pair in turn if that's easier to follow. The slice is more efficient, though, so better for very large data sets.

  my %new_row_data = (new_name => $name, new_ad1 => $ad1, new_City => 
+$town, new_z_code => $zcode);
  foreach my $key (keys %new_row_data) {
    $row->{$key} = $new_row_data{$key};
  }
[download]