What is the most humane way to trap mice?

Anyone know a good method of trapping mice humanely? I’ve got lots of them scurrying around. I bought two humane traps and have so far caught ten of the creatures. But there’s a design flaw; the mice get trapped inside a narrow black box for far too long. The manufacturers say the mice shouldn’t be left inside for more than six hours – but of course they are caught at night, just after I’ve gone to bed, so they ALWAYS are left for more than six hours in the trap. Inside they are terrified and get way too hot. Of the ten I caught, one died and six or seven were in a pretty bad shape when, having walked the statutory two miles (so they can’t come back), I let them go. I realise some of you may be unsympathetic towards mice and would dispense with the humanity stuff altogether. But they’re sweet little beasts – I just don’t want them running around my kitchen. I’ve done the ‘block the holes and keep everything swept clean’ bit, but this is an old house and there are too many entry points to cover. Please don’t suggest a cat: I’d rather be overrun with plague bearing rats than have one of those things. Anyway, advice gratefully received…