Are they Sugababes? Aren't they Sugababes? Should they change the name? Should they not perform old tracks?
Who knows...more to the point who cares. All I know is that "Sweet 7" is their best album in a long while. Heidi Range to me has always been the best member of the group anyway - After all, they really became succesful/known since she joined the group.
But I don't get calling them fake. Their label owns the name, always have done, so what is fake about it? It's just a name they perform under. Call them something else if you like. It doesn't alter the fact that currently, they are making good music.