There isn’t really a ‘they’ in the OpenStreetMap project. This geodatabase/map is being created by thousands of volunteers world wide (and some people being paid by big company’s).
as silversufer mentioned, the best way is to register and become part of the mapping community. New volunteers with local knowledge are very helpful.
Another way is visiting OSM.org, finding said area and leaving a ‘note’ by clicking the second to last button on the right and then on the location of the map. But depending on how active the local community is, this might take a very long time (if whole roads are missing, it’s likely there isn’t a very active community I’m the area yet).