Save As PDF And (please do not) Overwrite Existing

Any help appreciated!

When saving .xlsx files with the command ActiveWorkbook.SaveAs I get waning that says the file already exist.

But the codes below which prints the pdf file to specified folder, it overwrites every time.
How can I get notified that there is already existing file?

  Dim PdfFileName As String
  Dim Wsheet As String
  
  PdfFileName = Range("P1").Value & "  " & Range("H11").Text & "  " & Range("H12").Text & "  " & Range("C12").Value
  Wsheet = ActiveSheet.Name
  
  ActiveSheet.ExportAsFixedFormat Type:=xlTypePDF, Filename:= _
  "C:\Users\cangokturk\Desktop\Invoices\" & PdfFileName & ".pdf", _
  Quality:=xlQualityStandard, _
  IncludeDocProperties:=True, _
  IgnorePrintAreas:=False, OpenAfterPublish:=True

Cheers!