sono nuovo del vbs e quindi vado a tentativi, prova così
codice:
FileOrigine = "F:\Documenti\VBS\1.XLSX"
DestFile = "F:\Download\1.CSV"
Set fso = CreateObject("Scripting.FileSystemObject")
Set f1 = fso.CreateTextFile(DestFile)
Set ExcelApp = CreateObject("Excel.Application")
Set MySheet = ExcelApp.Workbooks.Open(FileOrigine)
For each sh in MySheet.Worksheets
  Set zona = sh.UsedRange 
  For RowCount = 1 To Zona.Rows.Count
      s= ""
      For ColumnCount = 1 To Zona.Columns.Count
        s=s & Zona.Cells(RowCount, ColumnCount).Text & ";"
        If ColumnCount = Zona.Columns.Count Then s=left(s,len(s)-1)
      Next
      f1.WriteLine s
  Next
Next
f1.Close
MySheet.Close
Set MySheet = Nothing
Set zona = Nothing
ExcelApp.Quit
Set ExcelApp = Nothing