Where did the manager do the shouting and threatening? If the answer was in full
view and hearing of the public then the manager has issues.
I agree with Old-Geezer that it is to do with terms and conditions, however the threat
of discipline is not worth worrying about as a good union rep will get it kicked out. No
problem.
Shops offices and railway premises act 1959 gave a minimum temperature not maximum.
This has been replaced by Health and Safety at Work Act , but even this does not give a maximum temperature.