Brakes locked on

Help help - quick quick, I'll be late for the spin!
Both brakes on the bike are locked on (Shimano Saints) - they were fine before the big feckin freeze but now the wheels won't move
does the cold affect brake fluid?
have tried heating the callipers with a hairdryer but no go.....

chances are the metals have contracted, causing an interferance fit. hairdryer will be too slow. leave the bike in the house for a few hours. possibly try hot (not boiling) water?

thanks fecker
i'll see what happens