Breech ( rather hind feet comeing out first) can be pulled successfully, best if you have OB chains or rope, a pole puller is best if you have one. That calf needs to be out as fast is possible, because once that umbulical cord breaks they will try to breathe and can drown if there head is still inside Mamma cow. I know it sounds cruel, but after a breech calf was born, we would hang the calf upside down for a minute or so on a board fence so the fluid could drain out of the lungs and throat, and then drop him down on the ground and stuff a thick straw up the nose to make the calf sneeze and cough good and hard to get rid of the fluid that it may have in its throat.
Like hooknline said, hope the vet had mercy on your wallet. They are none too cheap around here...
Nite Hawk