Housing Advice. How do you get help to find a flat? Particularly when you get benefits.

Yesterday I asked. a well known housing charity if there was anyone who could help someone with ASD. Dealing with letting agents, all the nonsense designed to stop people receiving benefits from renting flats. It's all totally bewildering and it seems there is no one out there to help.  

Am I missing something here? Because, It doesn't make sense that this isn't a thing.