I had the same issue. I'm "new" to FF XIV, started a week ago, but I did try it back in the ps3 days. I got lucky and tried the trial edition before I bought the game though, but it wouldn't even let me boot up the game on my ps4.
Contacted SE and, like you, they told me to contact Sony. Contacted Sony, and they told me to contact SE.
The solution I came up with was to create a new email address, set up a separate psn account, then used that to purchase and play the game with no issue. It sucks that the game isn't on my main account, but the game is completely worth it, in my opinion. Couldn't get out of the run around loop, so came up with my own solution. Hope it works out for you!