I had the exact same issue and its very frustrating! I also took mine to a few different garages, they used there longest bar and then they used a high power air gun but the inside of the key was starting to fall apart.
In the end i got a a breaker bar with a long metal pipe on the end of that so there was heaps of leverage, and then i pushed onto the key so that the key was sat on tight with no risk of it slipping off, and my mate cracked it off with the bar.
It might be worth a try getting someone to hold/push the key on the bolt while you try and crack it off, makes a big differance to how much strength you can put into it.
Hope you get it sorted.
In the end i got a a breaker bar with a long metal pipe on the end of that so there was heaps of leverage, and then i pushed onto the key so that the key was sat on tight with no risk of it slipping off, and my mate cracked it off with the bar.
It might be worth a try getting someone to hold/push the key on the bolt while you try and crack it off, makes a big differance to how much strength you can put into it.
Hope you get it sorted.
