We tried Killers extermination company years ago for ants and spiders, we had them come out once a month to take care of it. The first few months, things seem to get better. Then things started going back to normal, lots of ants , lots of spiders. I called the Killers to let them know . The came out to inspect, sprayed a little and left. The next month the spiders were back, I called and got the "Oh this is the time of the year they are out in force" So the next month I asked my neighbor to watch them for me. HE watched the guy pull in to the driveway, sit in his truck, eat lunch , write the bill and leave. The only time he got out of the truck was to place the bill in our door. The next month the same thing, this time my neighbor filmed them. I called , they gave me the "That would never happen, our tec are professional! " I told them my neighbor videoed the whole thing and asked if they wanted a copy. I was told "How do I know your neighbor didn't edit it to make us look bad" They never came back, they did try to bill us for the month that they never came out. After a phone call, they decided that they wouldn't charge me and never came back.
My lesson learned, ALWAYS make sure someone is there when exterminators come to your house to do work.