It is worth saying on the page that lists the repairs, because it is the least commercial sentence here and it is true. A dishwasher that will not drain is a tub filter, an air gap, a disposal plug or a drain hose loop far more often than it is a pump — and three of those four are outside the machine. A downdraft that has stopped pulling is a filter or a damper before it is a blower. An induction zone that cuts out is usually a cabinet with nowhere to breathe. A cabinet that will not hold temperature is a door seal long before it is refrigerant.
So the visit starts with those, not with a parts order. If it turns out to be one of them, you pay for the visit and we tell you how to stop it happening again. That answer is worth the same to us either way.