in reply to which modules to be used..???
Depending on the contents of your Excel files Spreadsheet::ParseExcel::SaveParser (a combination of Spreadsheet::ParseExcel and Spreadsheet::WriteExcel, also worth familiarising yourself with) may be all you require. Note the "Known Problems". If on a Microsoft Windows platform you can use Win32::OLE to drive Excel, provided you have Excel installed. Failing that you can try to automate Libre/Openoffice on other platforms (see Re^5: Converting doc to txt without WIN32::OLE or search for more references).