What if Landlord had your apartment exterminated only for roaches knowing that you have a bedbug infestation Landlord refuses to do anything else and will not pay for any more exterminating?

First of all, who caused the bedbugs? Unless you just moved in, or live in an apartment building, it will be assumed that you brought in the bedbugs. Even in an apartment, if no one else is having bedbug problems, and you are not a new tenant, the bedbugs are presumed to be your fault. Therefore, the landlord has no duty to exterminate them, though he may do so and demand that you pay the cost.

If you did not bring in the bedbugs, talk to a lawyer, as the landlord may be violating the implied warranty of habitability.