Don't give up on the key either.
Little hint ; it seizes up around the outside of the barrel, so with the boot open spray on and leave a pool of WD40 in the slight recess around the barrel, it'll get in there and work its magic.
I always struggle to get the key in ours, so I've made a point of getting busy with the WD40 once or twice a year and slowly teasing it back to rotating. It does eventually turn, but don't get too heavy-handed and snap it off!
