What can you do about it? You are paid for your job so why are you allowing yourself to do more and anothers responsibilities? Either lower your standard. Continue to be disatisfied. Or act on it. Everyone needs to be valued and respected surely! If you are allowing this to happen then what message are you sending out? Some workplaces dont care so long as the jobs done however their is dignity at work policy. Also, if you are giving the impression its ok then in many cases no-one will do anything.