you can compact your code by using the listindex property to generalise the routine:

   Private Sub cmbcontact_Change()
    Dim kk As Integer
    
        kk = cmbcontact.ListIndex
        Call ClientContact(kk)
    End Sub


     Sub ClientContact(kk As Integer)
     Dim ra(1 To 6) As Integer
       ra(1) = 3
       ra(2) = 3
       ra(3) = 6
       ra(4) = 6
       ra(5) = 9
       ra(6) = 9
   If kk > -1 Then
     With Sheets("Contact Details")
      inarr = .Range(.Cells(1, 1), .Cells(11, 7))
     End With
     With Sheets("Summary")
      For i = 1 To 2
       .Range("J" & 8 + i) = inarr(ra(kk + 1) + i - 1, 5 + i)
      Next i
      addi = 0
      For i = 1 To 6
       .Range("K" & 4 + i) = inarr(4 + kk, addi + i)
       addi = 1
      Next i
     End With
   End If
     End Sub