Replacement tubing shouldn't be a problem, standard stuff. Take off one of the bits and take it with you to any autoparts place as a sample to get the size right. You may have to also extend the white nylon tubing to the gage to get it to reach the right place.
Better yet, take the whole job back to your "installer" and make him fix it.
Better yet, take the whole job back to your "installer" and make him fix it.