Wow, i've seen sticky pins but never seized ones - i'm sure you wont fail to lube the new one now!
Soak it in the rust-solvent for as long as possible. Then i'd try to loosen the pin up some by shoving a large screwdriver between the pad and rotor and wobble the caliper back and forth as much as it will go. Also i'd have someone apply the brakes off and on while tapping the pin area with a hammer. Then i'd have a go at beating out the pin. The pin is history so you will need a caliper hardware kit.
I dont know the availability of caliper rebuild kits in Canada- but if you have more time then money, i might try rebuilding it. The caliper rebuild kit is just a few seals and so it is usually cheap. If in doubt about the caliper, just change it.
Usually if they carry seafoam chances are they will have deep creep as well.
If not just put the can kind in a generic spray bottle, it's the exact same stuff. Empty it back in the can after you are done cause i'm sure it will eat the plastic after a little while.
