I am not PADI, I'm SSI and I have to say SSI has always been responsive to me. I am currently in "Retired" status and still get regular updates from SSI.
That said, when writing in to a big organization with a complaint there are a couple things to remember. First, it helps if you can address your communication to a specific individual. In this case, whoever is in charge of curriculum at PADI. At SSI we have a top executive who is in charge of the program. Second, if you are expecting a reply, you really need to make that clear. You need to ask a specific question or say something like "please send me your thoughts on..." Lastly, complaints to an organization by someone in that organization, shouldn't just complain, but contain specific recommendations to fix the problem.
That said, when writing in to a big organization with a complaint there are a couple things to remember. First, it helps if you can address your communication to a specific individual. In this case, whoever is in charge of curriculum at PADI. At SSI we have a top executive who is in charge of the program. Second, if you are expecting a reply, you really need to make that clear. You need to ask a specific question or say something like "please send me your thoughts on..." Lastly, complaints to an organization by someone in that organization, shouldn't just complain, but contain specific recommendations to fix the problem.