A service here is filters washed, the indoor coil actually cleaned rather than wiped, the drain tray and line cleared, the outdoor coil washed, and the gas pressure read and recorded on your docket.
The recording is the part nobody else does and the part that saves money. A unit whose pressure was noted last March is a unit where a slow leak can be seen, rather than a unit that gets topped up every year by somebody who never writes anything down.
A unit genuinely short of gas has a leak, and a top up is a way of charging you for the same fault annually. We will find the leak or tell you the unit is finished, and we will not sell you the third top up.