Something like remind us (too indirect? general case?), or better settle up (like, settle a bill). Or something like that, a bit more equally balanced (even i

Something like remind us (too indirect? general case?), or better settle up (like, settle a bill). Or something like that, a bit more equally balanced (even if the obligation may not be), rather than final notice from the debt collectors :) Because that's the point, right? A gentle but firm hint?