I suggest you take some pictures. It's hard to imagine that they punctured the unit's walls. Seems it's more likely to have been affixed underneath. Is there a removable cover at the bottom of the fridge? Or maybe look underneath the caravan to see if there are any bolts in that spot. If there's a cabinet under the sink, you might look to see if there's any attachments you can reach through there. And the screw or bolt head may be hidden under a cap of some kind. It would look like a small button. Usually you can easily pry them off to reveal the bolt underneath. Hope that's helpful.