Most of us have seen the film Men In Black, but belive me cockroaches never get that big.
Dont be embarrased, Its not personal:- they can find there way through walls, floors, ceilings etc...........its just life
They can take upto 6 weeks to properly control/eradicate, it is a matter of wearing them down with treatments and cleaning, they hide behind Ceramic Tiles, under Floor Tiles, in electrical outletts, backs of Fridges/Freezers by the motor, in seals of doors etc....................................
If there was a nuclear war they would be the survivors.
It is not a 5 minute job, so if you are quoted a silly large or small amount, question what you are getting, it will take several visits, with lots of care and consideration to the environment that they are in-habiting.
For a free Survey call 01296 770214