How can I convert an excel document to a datatable and update cells in the excel sheet? And then save the changes in my excel document
I think it can be done using Database activities and connecting to excel file thru ODBC though I did not try it.
here you may find more info: http://stackoverflow.com/questions/15844633/using-excel-as-an-odbc-database
Why not use ReadRange, and afterwards modify the datatable resulted and save it back to Excel using WriteRange?