Allocating Space forever is a joke! No choice but to uninstall :(

client.exe is just a stub that launches the other one. During open beta, GGG changed the name of the exe because of a conflict with some nvidia profiles. When they changed the exe name, they didn't want to break everyone's shortcuts so they left a stub exe in at the client but it launches the PathOfExile.exe

PathOfExile.exe is what does all the work. Is the real Client.exe