Broken airbag bolts stuck in front drive axle leaf spring

Have two broken off bolts that secure airbag support to leaf springs on the front drive axle on a Peterbilt 379, been told to heat the bolts but not the leaf spring, problem is bolts are broke off inside the leaf spring so there's nothing to really heat without heating the leaf spring up as well. Tried a punch and hammer as well as an air hammer with a punch and no luck at all. Just wondering if there's maybe something I'm not thinking of that may work. Any input would be appreciated. Unfortunately the truck needs to roll and replacing the leaf spring is not an option at this point lol

 

Here is pic of the bolts

 

Here is what I'm having issues with they are broke off in the leaf spring. Have the frame jacked and axle dropped and am lined up with the bolts pretty decent, just that they are being stubborn and am running out of ideas

 

No nut or head basically broke off flush with the leaf spring. Broke the heads off trying to heat it up some and try to work them loose.

 

I have an oxy-accetylene torch only problem is I'm worried about the flame heating the spring up too much, I got one of two out just now using a small map gas torch I have I heated it up from the bottom side which still heated the spring up but am I wrong in thinking that I'm safer doing it this way? Just worried about weakening the leaf spring considerably with using heat. I know heat has always been my friend with rust however lol