I have had reasonable success with using the Apache POI project for the XLSX and XLS. You might want to consider looking at the community edition of Pentaho Da

I have had reasonable success with using the Apache POI project for the XLSX and XLS. You might want to consider looking at the community edition of Pentaho Data Integration at the 5.0 level and up. It includes POI for XLSX. I use it all the time to deal with random spreadsheets full of data I get from clinical data (hospital reports). But I hate excel of any type for data. People randomly change formats and give me updated spreadsheets with 100K's of rows. Then seem surprised when their data doesn't link up with other data sources anymore . . .