Bee problem...?

Look to see were they go in & out. Drop a mothball in there. Don't get stung. This sounds more like wasp to me.  Look close are they the black bees? They will attack & kill you. 

Bees don't normally sit on walls. Wasps do, especially if the wall is very warm. This is what they Love. I have what look like wasps that build nests on my eves and in the rafters of my veranda. 4 to 6" in diameter. and open cells. Not a true wasp nest that is a grey bubble of wasp paper. I found out they were garden wasps. They eat meat, in other words any bugs that would be eating my garden, the wasps would tag them and get them out...and eat them. So beneficial for the garden. They do not pollinate and they do not get angry if your hands are near their nests(real wasps look to sting you multiple times.) Real wasps make their nests in rotted hollow logs or in trees. The garden wasp is new to me. I have been gardening for 20 years.

If you want to get rid of them then get a water hose and hose the wall down so it is cold and wet several times and they will move to a place that is warm and drier. They won't bother you.

It is obvious that the so called professional did not recover the queen. The queen merely moved to a new spot. The swarm follows the queen. I suggest that you recontact that professional and make him/her come back out and finish the job that you have already pad for!

your professional should have removed the entire colony, including the queen--I'd get another professional.

If the removal person got the queen, they would all leave, unless you have more than one hive. Once the queen is gone they leave. Get the person to come back and do the job right. Don't kill them, they are too valuable to the eco system.

Bees are not a problem. Wasps are.

Lotta bees in my house too, but we just leave em be