You're saying those photos are real? Don't 'insult my intelligence'. [=don't treat me as though I am stupid; don't expect me to believe those photos are real]
Most people were forced to work longer hours each week, and to 'add insult to injury', the company decided not to give pay raises.
They're understandably 'insulted' when no one asks for their opinion on a matter that affects them so much.
(..) l don't want to take it back. - This is not worth pounds. - lt is to me. - Did you bargain? - l don't care to bargain. That insults them. l don't believe that. l think that you're insulted by me somehow. l'd be very happy to obtain the correct price for this. l apologize if l appear abrupt. (..)1996 The English Patient