Downloading AC unity after getting a new xbox one because the old one was gliched.

Was the code redeemed to your account ? If so, you should be able to find the game in the "Ready to install list". If it's not there and going to the marketplace prompts you to purchase it again, then I'd suggest contacting support about it.

Phone support

Chat support

I didn't have Wi Fi for a few weeks, when i turned on my Xbox One, i went on some of my games only to realise the saves weren't there.

I started a new game of Ac Unity since my previous save was not their, after i got my Wi Fi back i started up Ac Unity and it came up with select save game, it had a option between 2 saves, the old save and the new save with no warning whatsoever.

So i assumed it was my old previous save, i selected old save but instead it was the new 3% complete save instead of my previous 89% complete save but for the rest of the games i got my saves back by syncing it, only Unity didn't have syncing like the rest
did.

You do not need an online connection to play your downloaded digital version of AC Unity. Even though you are not connected to the internet, on your Xbox One, first go to Settings, Network, and select "go offline." Then start up AC Unity.

The procedure would be the same with the disc version of the game.

I bought ac unity on xbox live on my new xbox one about three days ago but it takes literally forever for it to even try to install is there a way to either speed it up or get a refund?

Sadly no. AC Rogue was the last one to be made to Xbox 360. SInce then, the AC games have been made for Xbox One (Unity, Syndicate, AC:Chronicles, Origins).