interop csharp save as and replace

                
                        //So you can do this to stop DisplayAlerts from appearing:

myApp.DisplayAlerts = false;

//And then if you want to save with specifying a file name, you can do this:
//specifying a file name
myWorkSheet.SaveAs(filename, Microsoft.Office.Interop.Excel.XlFileFormat.xlWorkbookDefault, Type.Missing, Type.Missing, true, false, XlSaveAsAccessMode.xlNoChange, XlSaveConflictResolution.xlLocalSessionChanges, Type.Missing, Type.Missing);
myWorkBook.Close(true);