How are you going about it just using filler ?
Take the badge out, filler it in, smooth over with 150 sandpaper, snap off the worms you get comin out of the badge holes. I 1000 the whole bonnet aswell cus it was in a bit of a state and was gonna paint the whole thing, go over the filler with finishing filler (bit finer for any air bubbles), primer the filler and any spots where youve sanded down to the metal with high build primer, sand that lightly to get rid of the rough surface with 1000 (always use soaking wet btw), n paint. i used cans and got an orange peel effect so now im using selulous paint from a gun, ill post pics after its finished.