The new owners won't take proper action on this building. They spray once and hope that works, but the reality is that *there is no chemical that can kill a bedbug*! The exterminator claimed that he hit us so hard with the chemicals and diatomaceous earth that it would penetrate the walls. That complete bull. The only thing known to kill an egg is freezing or heating to extreme temperatures for extended periods of time.
The owners refused to exterminate more than once a month, so we had to
pay our own guy to exterminate another three times (the minimum required exterminations each month to kill bedbugs). We sealed every crack in the apartment (no small feat!), put all of our things into plastic bins, sent them off to storage for the year, and finally moved out.
Unless the landlord treats the ENTIRE BUILDING and does so FOUR TIMES in ONE MONTH, they won't ever be able to take care of the problem.
Bed bugs feed on you, then can lay up to 5 eggs a day, which hatch anywhere form 7 - 14 days after being laid. 2 weeks and you've got 5 times the infestation. The only way to handle this is repeated treatments.
If you insist on staying in the building, pay for your own guy to come every week for a month and then twice a month after that until you're convinced the problem is solved. Also, seal up every crack in the apartment (EVERY one), as well as the outlets and light switches. And treat the apartment and furniture every few days with diatomaceous earth, vacuuming it up and re-treating the place periodically between exterminations. Also, make sure you've got a good exterminator - he should come in wearing a wetsuit! If he's wearing anything less, he's not doing the job right.
My suggestion, though, is to pay for your own treatment, then send your stuff to storage and live out of a suitcase in a new apartment for 18 months. It's the best bet to being free from them. Of course, the psychological damage they do is another matter...