at first: Allthought your situation may be unbearable, It's legal. As far as I know there are no standards or laws in Germany, that contradict to that. Please consider there is an extreme housing shortage in some regions of Germany, it existed even before reufgees come to us, so it's probably hard for administratiors to find an alternative housing for you.
I would advise you to wait 'till your interview took place. In my point of view after that you may be in a better postition to ask the proper town administraiion to improve your housing situation.