Creating csv files from Excel file

[Yoriz]

        ...
        etc = ExcelToCsv()
        df = excel_to_csv(xls_name, sheetname=sheet_name, startrow=start_row, endrow=end_row, csvfile=csv_file)
        ...

You have created an instance of ExcelToCsv but not called its method excel_to_csv
change it to

        ...
        etc = ExcelToCsv()
        df = etc.excel_to_csv(xls_name, sheetname=sheet_name, startrow=start_row, endrow=end_row, csvfile=csv_file)
        ...