the electromagnetic plug ins are excellent m8 i caught a load in traps and thought about putting poison down, but if you put poison down they have to die somewhere and if they die under the floorboards you are going to smell them rotting away!!
the plug ins take time to work and dont drive them away instantly, might take a week or so. the ultrasonic is useless unless you are in a big open space as it only works the same as a torck, whereby it is only effective if it is pointing at the mouse, and as mice stay close to walls and mostly under cover the ultrasonic waves will miss it.
if you are putting down traps put them close to the wall but not touching and put something on that they have to get on the trap for, i started using kitkat but the buggers just leaned over and ate it. i ended up using the hard dog food wet is slightly and force it on and cover in peanut butter (a nice last meal)
if i were you keep using the plug in and trapsand leave the traps down even after you think they are gone, and i still use the plugin a year after they are gone to stop reinfestation.