The best way to kill an infestation of roaches is by removing access to food, water and fat (grease on fans, walls, vents, etc).
Then use a roach bait, ideally the kind in syringe applicators.
Inject into virtually every nook and cranny you can. The bait is the most efficient method of eliminating the infestation. It will take longer to eliminate all of the roaches, but once eliminated, as long as you are tidy (have no food or grease available to them) your likelihood of reinfestation is slim.
From there, you’ll want to keep vacuuming up the dead roaches, and wash all corners and crevices you can see their fecal matter in. If you can locate the nest, don’t disturb it. Instead, poison heavily in the crevices near it. After the nest is thoroughly eliminated wash the area well, and reapply the bait in case there are any stragglers.
As a property manager I’ll add this: It would be wise for you to let your manager/landlord know there is still an issue. The landlord should be using bait, not sprays to kill off the roaches. Sprays and forgers kill what you see….not what you don’t see.
If they have already called out a pest control company, then they already knew the issue existed. It’s their job to follow up on this for the health and safety of their tenants.