Have a look on openstreetmap.org map to see if those addresses you have searched for are mapped.
You may find that the Garmin suitable osm maps for your area may be fine for the road network but are lacking address details.
For my country the best that can be expected is to find the street name and town but not the house numbers and I expect this is a common situation in most countries.
The $400 you pays pay buys comprehensive datasets I expect, but I have a new Toyota and the address details and trying to enter a route are very poor so far for such expensive equipment and they charge over $300 for updated maps, so throwing more money at the problem does not always help.
I wish you well with solving the address problems in the osm map for your country.