Most people book pest control while mildly panicking, from whoever answers the telephone first. That is understandable and it is how the wrong job gets done. These are the questions worth asking before anybody opens a container in your home, and a good operator will answer all five without hesitating.
1, What exactly will you use, and what is its registration number?
Every pesticide sold legally in Sri Lanka is registered with the a licensed distributor and carries a number. Ask for the product name and that number before the visit, not after. You can check it yourself, and the answer tells you whether you are dealing with somebody working to a label or somebody decanting from an unmarked drum.
2, How long before we can go back in?
Re-entry time depends on the product, the concentration and the room. It should be given to you before the work starts, in writing, along with anything you need to do first, covering an aquarium, moving pet bowls, emptying a cutlery drawer. A shrugged "give it an hour" is not an answer.
3, What happens if it does not work?
Some jobs need a second visit by design; cockroaches almost always do. Establish before you pay whether follow-up is included, how long the cover lasts, and what triggers it. Termite work in particular should carry a written warranty, and the length of it should be on the paperwork rather than in somebody's memory.
4, Is anything here going to make this come back?
A competent technician will tell you when the pest is a symptom: a leaking pipe feeding a termite route, a gap under a door, a drain that has lost its seal. Spraying a building problem is a way of being paid twice, and being told plainly that you need a plumber rather than a treatment is a good sign about who you are dealing with.
5, Will I get it in writing?
What was found, what was used, at what concentration, where, what the re-entry time was, and what you should do next. Without that you have no record if anybody in the household reacts to something, and no basis for a warranty claim. Ask for it as a matter of course.