Too darn hot

Back to work today - my return being made even less pleasant by it being over 80 degrees in my office nearly all day.

Air conditioning has been broken over a month, engineers can find nothing wrong and we've been given 3 measly fans to compensate for not having any windows that can open.
As far as they are concerned they've done all they can for us, but what they don't realise is that I am IOSH certified (ooh smarty pants) and know that, despite there being no upper working temperature guideline, if they don't remedy the situation immediately then we are perfectly entitled to walk out because their 'best efforts' haven't worked!
Now we're trying to decide whether to...
- go now
- to persevere for the rest of the day and save the walkout for Monday when everyone else is on bank holiday except us
or
- throw a pc through the window

Hmmmm decisions decisions!