@Peter *********
that's nonsense and you need to NOT trust an immigration officer at the airport as far as what you can or can't do bouncing out and back by land. Border bounce is NOT illegal, and no matter what they tell you when you stamp in there is no official limit of free 30 day stamps entering by air
As long as you haven't done TWO land entries on free stamps in a calendar year you're fine to bounce out and back to get a new 30 day visa exempt entry stamp AND take a 30 day extension on that as well if you want to