I wonder, if I may, ask some more about your problem. I have a (small) interest in ParseExcel, as well as WriteExcel, as I recently wrote a script to deliver hundreds of Excel spreadsheets using the WriteExcel module.

You were saying that your customer generates an Excel 4.0 document, and that ParseExcel can't handle it - do you mean that ParseExcel just aborts on the file, or does it returns the kind of problems you were experiencing with OpenOffice calc?

Also, according to the CPAN documentation for ParseExcel, each cell object has a number of fields. They include: Value, Val, Type, Code, Format, Merged, and Rich. Which field were you viewing? Is is possible that if you were dumping:

  $oWkC = $oWkS->{Cells}[$iR][$iC];
  print $oWkC->{Value};
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that maybe the value you're looking for could be in:

  print $oWkC->{Val};
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?

Perhaps a contribution of:

  use Data::Dumper;
  print Dumper( $oWkC );
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might aid in your question here?