This happened to me last week. Bolt would spin freely but would not budge. I soaked it for days with penetratong oil and it still wouldnt move. Turns out I was NEVER going to get it with a hammer. I put the bike up on a steel table, tacked two tubesteel post to the table, one on each side. Then put a piece of steel pipe over the bolt head between the frame and tubesteel post. I then put a porta power between the bolt and other tubesteel post. It was so stuck the entire bike moved before the bolt budged so we had to tack a large piece of angle iron to the table and bolted it to the peg hole. We really cranked up the porta power and finally it jumped about 1/2" with a loud crack. Reset the setup and got it to move again about 1/2". Used a piece of round bar to get it about halfway through and then was able to hammer it out. It took so much force that the 1/2" thick steel table flexed almost an inch on either side before the bolt moved! So yea a hammer would NEVER have worked. But I saved the bolt.
