Low stations gone again

Every two to three weeks while watching channel nine all of a sudden it goes out and now they tell me oh we have to come out to your house and replace stuff. Last time they fixed it from the office. I work in healthcare and can not miss time from work and they won’t come unless I am here I have all my high channels but no low channels. I am so mad if it’s the dish why woul I still get channel five and channel four.