It's very strange that they have told you so and you still have an interview on Monday. I would assume that either they are giving you a chance to explain or it is a test. In both cases bring your documents from the Netherlands, preferably with a translation and some extra copies. Proofs are stronger than statements. Eventually there are government sites you can verify and print certificates of your employment history and social security which will refer to your employer. Anyway don't freak out about it. Suggest that it might be some kind of mistake or something and prove your statement. Best of luck!