FNB IS A DEAD END ROAD

My fnb account was put on hold 5 years ago, they asked me for documentation to verify my identity document of which I gave to them. They asked for proof of where the money came from and I also gave them yet the hold was not lifted, I've been given some story about ***** yet no investigation was done, I had the same issue with absa but the Hold has since been lifted. I would like to understand why fnb cannot do the same.