Ok so I managed to find a fix to this without EA's help. They have been unhelpful with all their flush dns or create a new administrator account or their other steps. I would suggest that you look for a fifa 15 torrent online and to download only these files:
- data_graphic2.bh
- data_graphic2.big
- data_graphic2_extra.bh
- data_graphic2_extra.big
Once you got these 4 files. Pause your current download and paste it in your fifa 15 folder. You should see some files saying "data_graphic2_extra.big DIP Staged " Something like that. Delete that. Then resume the download and it should tell you that the installation was complete and you will be able to play the game.
PS: It's because origin can't download the data_graphic2_extra.big file that it keeps getting stuck at 75%
