I had this issue with the place I'm staying at. There was a few cockroach at first but gradually got worst. I would kill like 20 adults each night, I only really see them late night. Our home is very clean as we have kids so helper cleans daily. I did a lot of research on this situation. First off the cockroaches you have are likely German cockroach. Worst of the breed since they lay a sh*t load of eggs and females carry their eggs on them. I see you bought a supermarket fumigator. Fumigation will kill the cockroach that are live but its ineffective against the eggs. I also went the path of buying traps and spray from supermarket, it was a waste of money in my opinion. I then got a professional company to come in to my place and then place a bug bomb in the house, left the house for 3 hrs, came back and picked up about 50 or so dead cockroaches plus assorted silverfishes. Cleaning up was a pain as it left a residue on the floor and furniture. Fumigation last for a couple weeks, then the odd small cockroach came back. I complained to the company since they guarantee no cockroaches for 2 months but they gave some lame excuses about fumigation is most effective for the existing roaches and not the new ones. I yell at them and they finally sent in another dude to lay down roach bait. Basically this white gel with poison in all the crevices of your home. The bait takes about couple weeks to work as the roach would ingest it will die eventually and other roach that ingest the poisoned roach will also die so it spreads around. The bait last for a couple months. After using the bait, the roach count was reduce to 0. Haven't see them the last couple months.... knock on wood.
Since I am currently renting I did discuss with the owner regarding this situation, they were understanding about it and split the cost with us for the professional help. Your miles may vary of course pending on your landlord.
So in summary, go professional, supermarket grade won't do the job if you have a bad outbreak....once the roaches are in your home, those biatches are everywhere... damn I hate them.... and yes talk to the landlord.
Sorry for the long rambling, hope this helps