What i did once was to hammer and chisel a groove on either side of the hole, and then hammer gently to turn it slowly. Not sure of that's what Laurence meant but hey gotta recover this mess somehow
Okay so you rounded the bolts? get a file and create 2 sides so you can whack on a spanner and undo them, if you havent got a file or the time, i suggest you take it to your LBS to see what they can do.
Or similarly, you can generally hammer a larger headed hex key in and make like a new groove, sometimes works but not as well as using the chisel method IMO
What i did once was to hammer and chisel a groove on either side of the hole, and then hammer gently to turn it slowly. Not sure of that's what Laurence meant but hey gotta recover this mess somehow
So much easier with a file, Once done, you can reuse the bolts again and again, all you need is a spanner