Dressel Divers offers "free advanced diving courses" and since there are 5 required adventure dives, you'll purchase some kind of dive package with them. Booking online gives you a 20% discount but it is also the only way to book the dives.
Dressel on Coz is located at the Iberostar resort. I took the "free AOW" (which is how it was advertised at the time) a couple of years ago when I stayed in Playa Del Carmen. One of the days we did 2 dives in Coz, one of which was the deep dive for the AOW. The dives work out to be really cheap $$. We did an 11 dive package which included cenotes and a night dive.
Plusses: low cost, well organized op, communicated through WhatsApp, all transportation included, stored our gear, initial contact and booking was pretty easy even though it's through their home base in Spain, being in Coz you should get to dive some great sites (PDC wasn't so great)
Minuses: resort op, so 45-50 min dives (2 cenote dives at about 40 min each)
I'm a vacation diver and my only goal was to get the card at a good price and only for the purpose that if I ever ran into some op that required it for a particular dive, I'd have it. Reading (actually skimming through) sections on the 5 dives I did for AOW were good in the respect it refreshed my memory on some things but the dives were nothing I had to train for and the skill/knowledge to pass them was pretty easy. Dressel was exactly what I was looking for. But like others have indicated, if you want to become a better diver, take the course with an op that will really teach you something.