Yep outside the EU is very tough. The Middle East are, in my experience, quite tough to deal with. We often invoice up front or the majority of it to avoid this in certain regions where we have found reputations are often not for nothing.
Don't listen to either of them. They are scaring you and Dutch courts absolutely will protect you. You can get an 'incassobureau' involved and I promise you, they will pay. Not paying invoices in The Netherlands can really mess you up as a company...