been coming here over 25 years, tbh can't say i've ever experienced bad customer service from an IO at the airport or immigration centre, they are certainly friendlier than some of the central american land borders i've crossed.
if you're continually getting poor customer service you need to manage your expectations, these are civil servants doing a responsible but ultimately repetitive, boring job. i'm a believer in what goes around comes around, maybe you need to look at your attitude?