Writing to Euro MPs, with good well reasoned information, is the best way.
They have it in their power to sink this dishonestly sneaked-in rubbish.
The problem is that most of them do not understand the issues they are voting on, and most of the smaller countries vote YES anyway because they have a straight need to brown-nose the EU. Can you imagine Greece voting against, for example? And that is a "big" place; there are umpteen smaller ones with a vote.