Can't play the full game on PS4

I'm trying to download the game but I can't because it says that I have already purchased it so I tried to download from my library and in the description says that it's the full game but when I try to play the game it's not the full game it's the demo and I can't download the full game so I tried to download directly from the game but it said that I already have the game I installed but this is not the full version I can't even rebuy the game.Please resolve this because I want to pay the full game.