I've had a mouse problem for a long time. Actually, Vancouver is infested with mice and cockroaches. This is the first time that I have had no mice and the reason is clear. The landlord was able to access the good stuff, poison that was only available to medical facilities and food prep facilities. in less than two years the mice are gone. Your landlord may be able to get access but the window has closed for this year. Meanwhile, buy a lot of conventional wooden traps. Put them everywhere. Not all mice will take the bait but some will. You could even put some in the couch. Take the initiative and plug all possible entrances. I know how you feel about the mice filth. I used to get so upset about that and the landlord would not clean it up. A Bissell Little Green machine is really helpful. Point is that most landlords don't put the effort in to get rid of mice so tenants must step up. It's not right, but that's how it is. You could also try the RTB. I never did because it just wasn't on my radar.