So a garage couldn't get one rounded bolt off??
If it was you trying, fair enough then
I've rounded loads the only real way is to either soak the bolt in plus gas over night then have ago.
Did they round it or did you see them try and smack a smaller socket to it?
The solutions are available such as DH mentioned, I prefer to just use a dremel to create new sides of a bolt or drill across the centre like a flat headed screw driver and then find the biggest flat head screw driver and use a monkey wrench for torq.
Other aftermarket options are bolt extractors tap and die sets, never used one no need as I usually put a bit of heat onto it before trying to get it off.
Worst case I've just ended drilling the bolt out it might take two hours slowly going up a drill bit size, but I leave enough bolt shell so I can just get plillars onto the thin steel shell and hey presto thread still intact.
Or drill it right out then helicoil not really good as helicoil is not better i.e less threads, ok for non load bearing bolts!
