Add shape only if shape doesn't already exist

[gtbreps_2]

I'm trying to add a text box shape. I have the code written to add the text box where I want it and how I want it formatted.

Dim Message As Integer
Dim messagebx As Shape
Message = MsgBox("Would you like to include a message to the client?", vbYesNo + vbQuestion, "Message")
If Message = vbYes Then
        Range("C12:L12").Merge
        rows("12:22").insert
            Set messagebx = Shapes.AddTextbox(msoTextOrientationHorizontal, 22, 165, 473, 185)
            messagebx.TextFrame.Characters.Text = "[Insert Message]"
            messagebx.TextFrame.Characters.Font.Size = 9
            messagebx.TextFrame.Characters.Font.Name = "Arial"
            messagebx.Line.Visible = msoFalse
        Else
        'do nothing
        End If

After this and a bunch of other code is performed, my sheet can be updated and the code re-ran. But if I re-run the code, this text box is replaced with a new blank box. I'd like it to just stay using an error handling statement or something. I'm just not familiar with error handling.

[gtbreps_2]

I solved my own issue. I simply added an extra user input box and rearranged a few actions. Used a yes/no box 'Message1' to give myself space 'rows("12:22").insert' because if I re-run the entire code, information gets replaced in those cells even if there's already a text box. Message2 is another yes/no box to ask if I'm creating a new text box or if the text box already exists. If I pick yes, it creates a new box, if no it doesn't insert a new box ... aka there's already a box there.

Dim Message1, Message2 As Integer
Dim messagebx As Shape
'User input to ask if there is or will be a text box to insert cells where text box will be located
Message1 = MsgBox("Is there going to be or is there already a message to the client?", vbYesNo + vbQuestion, "Message")
 If Message1 = vbYes Then
 rows("12:22").insert
'User input to ask if the text box is a new box or if there is already a box
  Message2 = MsgBox("Would you like to add the message to the client now? If you've already written the message, pick NO!", vbYesNo + vbQuestion, "Message")
If Message2 = vbYes Then
    Set messagebx = Shapes.AddTextbox(msoTextOrientationHorizontal, 22, 165, 473, 185)
     With messagebx
      .TextFrame.Characters.Text = "[Insert Message] *If new text box is inserted by accident, select box and delete."
      .TextFrame.Characters.Font.Size = 9
      .TextFrame.Characters.Font.Name = "Arial"
      .Line.Visible = msoFalse
      .Placement = xlFreeFloating
     End With
    Else
    'do nothing
   End If
Else
  'do nothing
    End If