Take a look at this diagram. They will have ample things to put down these pipes. Heavy mud, junkshot, you name it. It will eventually work. This is the BEST and most obvious method to fix this. Barring heavy explosives, this is a winner. Give it time. It IS WORKING.
Also note, most of the oil that does make it up to the surface is getting skimmed and dispersed. So very little new oil is getting away from the leak site. Take a look and see for yourself.