My two bob's worth, Theseus, for what it's worth (two shillings?)
"πια" here expresses a remonstration/an annoyance - it's like adding: "already/"for goodness sake"/or an exasperated groan/ ahhh! :scared:".
So, "φτάνει πια" , for instance, would be "enough already/ enough for goodness sake (sort...