Why on earth would they even touch the prongs if they're just resizing the shank?? Did they switch rings on you?
Return the ring, get a brand new one and take it to an private jeweler who will take the time to size it right. Places like Tiffany's or Fortunoff's are churning adjustments around the clock, they rush through their work. I once requested engraving and I got back hand engraving but it was sub par, the letters were not straight. i.e. unprofessional looking.
That's my question too. There was absolutely no need for them to touch the prongs. I totally agree with this message. Return the ring. Go to a private jeweler to get it sized down.
Good luck.