Cockroaches in apartment! Landlord isn't trying hard enough!?

My family and I have been living in this apartment for the past 12 years and last year we started noticing cockroaches. The agency that the landlord has us under is very rude too. Since last year, they have sprayed our apartment and we are still seeing them. We keep complaining because we're tired of seeing them and packing up our WHOLE apartment every time they spray, and let me just add that we are not the only apartment complaining about cockroaches...there are 3 other apartments with the same problem. They recently just did the third spray and the manager at the agency got really mad at us for complaining and told us to not talk to him anymore because he's fed up with us. So now we have to speak to his supervisor. If talking to the supervisor and nothing works again. What can I do? It's nasty to find a cockroach is your bed and everywhere else!!! HELP PLEASE!