We had this problem last year - in a townhouse near Paris…what we would call ‘terraced houses’ with long collective roof space which provided a passage for mice to get between all the houses and into the walls.
A group of neighbours worked together to figure out where the wretched creatures were getting in and the hole was sealed…this is a very important first step otherwise you’ll never solve the problem. It’s also a good idea to keep a tidy house and keep all food sealed and in cupboards…no crumbs!
Then we called in a pest control company who sent a bloke to put down poison in the roof space once a week for about a month. Problem solved.
We have cats but they’re not much use against the rodents when they are in the wall cavities!
It’s an annoying problem, but relatively simple to deal with. I know someone who had bed bugs and that is a living hell, to be avoided at all costs.