First of all, how deep are the dents? Have they scratched the finish off the harp, or are they just “skin-deep”? There may be a method to correct them if it is the latter case. I can’t tell you the exact method, as it was only mentioned to me once by a luthier, but it had something to do with steam?? And since I am not sure what type of finish you have, I even hesitate to suggest this. Perhaps call a professional harp maker, or maybe Carl can jump in here with a more experienced response….
You don’t need a harp repairman to fix those dings. Just someone who is very good at finish and refinish work. There’s no way of saying how much it will cost until he examines the instrument. He may not be able to make them disappear, but rather make them less obvious. As an old finishing mentor of mine said”…take their trumpet away.”