I don't know of anyone that offers a resto service, but those emblems are pretty easy to do yourself if the plating is good.

Chem strip or lightly glass bead to remove the paint

mask the back of the emblem

Paint the entire front of the emblem black (I use testors "black chrome trim" paint sprayed with cheap air brush). I'm guessing you can find a rattle can of something similar.

Let the paint dry in the sun or bake it at low heat for a bit to cure.

Use a q-tip with laquer thinner to get the black off the face of the letters. Go easy on the thinner and blot the q-tip before applying and work one small area at a time.