If you want to use case statement I would then perform this:
Dim bHandled As Boolean = False
Select Case e.Modifiers
Case Keys.Control
If e.KeyCode = Keys.Oemplus Then
MsgBox("KeyPress CTRL + OEMPLUS")
e.Handled = True
End If
If e.KeyCode = Keys.A Then
MsgBox("KeyPress CTRL + A")
e.Handled = True
End If
Case Keys.Shift
If e.KeyCode = Keys.Oemplus Then
MsgBox("KeyPress Shift + OEMPLUS")
e.Handled = True
End If
If e.KeyCode = Keys.A Then
MsgBox("KeyPress Shift + A")
e.Handled = True
End If
End Select