1) Use plenty of oil/WD40/bear grease and work the bolts back and forth. I mean tighten and loosen. Do this gradually and try and loosen a little more each time. Take your time.
2) If you strip all the splines on the bolt head, get a slightly smaller socket, e.g. an inch size socket and hammer this on.
3) Get a big nut that will fit over the head of the bolt and MIG weld this on.
4) Cut off the bolt heads, remove the swaybar and bushes etc. Apply some serious heat and try with vise grips. Or lock two nuts together on the bolt shaft and try the heat.
Note: If these bolts are serious metal, heating and slow cooling will draw the hardening out. This can be bad as it will increase the chance of snapping, but good in that if you have to drill out the snapped off piece, at least it will be a little easier!
Get a swear box. By the time you have given up and called in the experts, you'll have enough money to pay the bill...