Removing Rear Brake Caliper

[melv1golf]

i actually have a 1999 ford cougar but i think the rear calipers are the same as the mondeos, I am trying to change the rear pads and discs but cant remove the caliper, i believe that you have to undo the retaining bolt with a 7mm allen key, i have tried with a good quality hex socket but all i have done is round the head so i now stuck, the obvious thing to do is cut the bolt but once i have done this how do i then remove the bolt, i hope this is not to confusing and even more so i hope someone can help me

[fishpond 47]

The proper 7mm allen key (caliper tool) cost's under a fiver from Halfords, have you tried a pair of mole grip's on it now?