Welcome to the forums Neil.
Just an amusing side issue, here. I was interested in the place where you live, so I thought I'd have a "walk round" on Google maps. Go to the street where Carrefour Market is (it doesn't seem to have a name) and see if you can spot the man and woman at the northern...
Rats are very intelligent creatures.
If you are using a trap, then bait it but don't set it. Do this for about a week. Then set it! This strategy usually works.