they close completely but there are gaps at the bottom of one of them and you can see what I have on the inside ledge and my living room floor. Personally I dont think they will come back - once they get your money!!!!
Are they fully dropped and are they facing the right way?
To blackout the outside, you want the curve of the blind to be facing outwards. The "hump" on the window side and the "dip" on the inside.
Done what you suggested Mo and it is far better. I have had venetian blinds for a lot of years but never had to do that - the "hump" was and still is inside.