Help..92 SEVILLE .emergency brakes locked on

Apparently I put the emergency brake on before putting the vehicle in storage.
I fired it up and found the rear caliper assemblies were corroded "On"..
My hinter land mechanic says they cannot be bathed in WD-40 or equivalent...and that the calipers need to be replaced...$500 parts and labor.
What say you?
RSVP here please.....thanks
The Good Guys and the Bad decide: / /

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