Hello qatn,
Thanks for posting here in the Apple Support Communities. I see from your post that you are attempting to use the Complete My Season feature, but you're having trouble getting it to work the way you'd expect. I can certainly understand why you'd want to take advantage of this reduced price since you've discovered you like this particular TV show.
As a first step, I'd recommend that you try restarting your Apple TV. Take a look at this website for information on how to restart this device:
How to restart your Apple TV - Apple Support
If you are still having the same issue after restarting, it may be a good idea to try completing this purchase using another device. If you have a Mac, PC, or iOS device available, you can follow the steps here to complete a season:
Complete an album, season, or bundle
On your Mac or PC
On your iPhone, iPad, or iPod touch
On your Mac or PC
- Open iTunes.
- Go to the iTunes Store.
- Depending on what you want to complete, choose Music, TV Shows, Movies, or Apps from the upper-left corner.
- Under Quick Links on the right side of the window, click Complete My Album, Complete My Season, or Complete My Bundle. Any eligible albums, TV seasons, movie bundles, or app bundles appear.
- Select the item that you want to complete. On the item's Buy button, you'll see an adjusted price based on what you’ve already spent.
- Click Buy.
On your iPhone, iPad, or iPod touch
- Depending on what you want to complete, go to the iTunes Store app or App Store app.
- Find the album, season, or bundle that you want to complete. On the item's Buy button, you'll see an adjusted price based on what you’ve already spent.
- Click Buy.
About Complete My Album, Complete My Season, and Complete My Bundle - Apple Support
If you still continue to have similar issues when trying to complete your purchase on another device, it may be best to reach out to iTunes Store Support for further assistance with your purchasing issue. You can do that using the following website:
Contact iTunes Store Support
Take care!