I don't find it that hard with oil change: As long you know the temperature of the gearbox..
Run it to correct temperature (53-57c)
Go through all gears for 3s each (P, R, N, D, S/1, 2)
Remove both bottom ones and put them back
Top up about 7 liters (Said so on Ford Etis, same gearbox)
Tighten top-plug, not hard. (If you need to add more oil)
Start the engine and leave it on.
Go through the gears again when gearbox reached correct temperature
Remove the smaller bottom plug, still engine running.
When it stop dripping, tighten the plug.