A VERY unwelcome house guest! HELP!

I spent two and a half hours this morning, watching a mouse that kept appearing on my main floor. It was obvious that it wanted to go down to my basement, but I wanted to make sure it did not come anywhere where I was sitting instead. They scare me to death! The exterminator had just left - his second visit, the first one being just before I left for my two-week trip to Ontario and Quebec on 6 May. I had hoped all would be solved by the time I got back, but no. The mouse man had put about half a dozen small boxes on the main floor and in the basement, and when he checked the sachets inside the boxes today, he found that there were a few nibbles upstairs, and more nibbles down in the basement. He said he could tell it was not a huge problem, i.e. not a lot of mice, but even one mouse is far too many, filthy little things, and I have been a nervous wreck ever since the first sighting almost a month ago. The man will come back in a month's time, but I don't think I can take it for that long. Not sure, though, if I'd be able to put out a more drastic box or two and have the mice die inside them. Ha, I'd never be able to remove the boxes to the garbage!!! Sigh.

A number of years ago, several of my neighbours in a different building had mice indoors, but this is the very first time I have had any (as far as I know!). I wonder if they can get in more easily because there are no protective layers between the siding and the inside of the place. There is a huge, extremely costly repair going on for the whole complex because, when the siding was last replaced, it was not done properly.