Give as good as you get.
They don't want to be grateful when you save someone's life. Fine. If they don't value the service, don't do the service. And rub salt in by being first to call dibs on the dead Bozo's equipment.
They want to use people as meat shields. You are far better at that game then they are. Once they've pinned down several monsters in melee. Let loose an area effect spell. Thank them for the way that that they created the opportunity afterwards. And make sure you are first to call dibs on a dead PC's equipment.
As you get to higher levels, your ability to screw them over more than they can screw you over should teach them to play nice.
Don't get mad, don't get whiney, get even. And if they complain, suggest a nice friendly one off session of Paranoia to let tempers cool down.