This isn't really an immigration question so I would recommend that you speak with a benefits lawyer but it's always a good practice when something like this happens to submit FOIA requests with the appropriate agencies to try to find out what's going on.
Thank's for the tip. I've known about FOIA requests but never fancied I could create one myself.
It's more an issue with benefits than immigration like you say, but I just assumed I was treated badly because I was an immigrant, so immigrants beware.
Also I wanted to play nice I thought if I caused some trouble for them they would definitely treat me even worse. Immigrants don't have a similar feeling about their "rights", and what they can do, as perhaps native-born Americans have.
