Which department should I respond to if I can't get the reservoir resettlement money?

The local resettlement office is mainly responsible for this. Go and have a look. Reflect problems to the bureau of letters and calls or the district government, and there is a district head who is responsible for reservoir resettlement ~

Legal means should be useless, and the law is basically for the government. . . .

The media should be good. Find a few people who have the same problems as you, find some columns that specifically reflect people's livelihood, and take them seriously.