iPhone 6S restore leaving greyed out apps

Hi Guys,

I had my iPhone 6S replaced at the genius bar and have been trying to restore using my iCloud backup. Despite leaving this for about 36 hours the vast majority of my apps will not download and appear with darkened icons.

I've read that this is to do with app thinning, the only app that I really need to "save" is WhatsApp as it contains all my message data and media. I don't have a separate WhatsApp backup as my complete iCloud backup has always covered this.

You can force apps to download by heading to the app store and hitting the cloud icon, however I've noticed that this would override any data as it is a fresh install.

I've looked in to my iCloud backup on another device and my backup is definitely complete, it shows that my WhatsApp backup is about 1.5GB, quite large but shouldn't take days to download on a quick wifi connection.

Any ideas?

Thanks,