The steps to redeem a gift card on an existing Sling TV account vary based on whether you want to change your subscription or just add the gift card balance to your account.
Start by visiting sling.com/account
and log in with your email and password.
Scroll down for details on how to redeem a gift card. To see details on how to change your subscription using a gift card, click here
Redeem gift card only
To redeem a gift card without making changes to your subscription, from the My Account
page, click on Add Gift Card.
Type in your gift card number and click on REDEEM.
You'll be notified with the amount on your gift card. Now click UPDATE.Redeem a gift card and change your subscription
From the My Account page, click on CHANGE SUBSCRIPTION
Edit your subscription the way you please by selecting or deselecting the services you want to add or remove.
Before you review your new subscription, scroll to the bottom of the page and select Redeem a gift card.
If your account is gift card-only, you'll select Review.
Make sure your billing address is updated, then add your gift card number and click Apply.
Once your gift card has been applied, click Continue.
You will then be able to review your subscription and submit your order.