The taxis are truly awful. We have been to Plakias quite a few times, always arriving at Heraklion airport. We only used a taxi once, to get to the airport from Plakias, and I never want to do that again. They drive far too fast and very often on the wrong side of the road.
The buses are much safer and much cheaper but very slow and you are likely to have to change in Rethymno. Not much fun with your luggage.
The best way is to hire a car, either for the whole holiday or just 3 days either end.
If you want to do that, you could contact Adonis at
Anso Travel in Plakias at
who will arrange whatever you want.
If you must have a taxi, Adonis could also arrange it or you could just pick one up at the airport.
Enjoy your holiday!