Employment advice/legal aid for foreign worker

Is there a legal service/organization that can help me as a foregin worker here in Brussels? Specifically as a teacher? My situation is this, a work permit was not applied for during this time (20 December to the 4 January) AFTER having been asked to update my Residency permit, which I did of course. My school did not apply for my Work permit and then claimed that I didn't get paid because I didn't have a Work permit. I have a paper trail from the commune showing that all necessary documents were provided to the school but they told me that I would not be paid (20th Dec-4 Jan.) on the 19th December. Very last minute/second, so I need someone to speak with me (English or German) and explain it all to me, so that I can understand how someone can get away with this? Thank you and any advise would be very much appreciated.