There's' a bug in the listing of shops under city. Sometimes the cities shown are different to the selected, here Porto as example:
It looks like those are the shops closest to Porto. If I click the Map view after using your search it appears the search is using Porto as the center and just showing the shops within a close radius to that city. Do you have a shop listing that is in the city of Porto that is not displaying?
You are right that there might be a issue of the address of two of the shops located in Porto. This seems to be the same problem on their FB pages, though. But look at the listings of shops i Portugal - all of them is listed at wrong cities, although address seems to be correct: