I see, ye the bolts are quite soft, have you tried braying a 21/32" socket bit over the bolt, thats just under 17mm so might just go on.
If not you will need a centre drill, an 8mm drill, a 12mm drill and an M14 x 1.5 Tap
Use the centre drill to get the centre point of the bolt, needs to be as central as possible!!! Then use the 8mm drill to depth, then the 12mm drill, you need to get these as concentric to the bolt as possible!!!! (Any bigger than a 12mm an you will damage the internal thread of the hub)
You should now be able to twist the bolt out, the bolt head might shear when you try this, if so, just scrape all the remains of the bolt out of the hole, blow it out and run down it with the M14 tap.
Or just come up to my work at Wortley next Sunday an we'll get it sorted.