How to use T-Mobile YouTube TV promo if I already subscribe to it?

Crookpro wrote:

Not true, you DO NOT have to cancel and restart. I got the link texted to me today and it appeared it would be as simple as clicking on the link. What really happened is it just opened YouTube TV on my computer/Phone. What you have to do since they sent a bum link is click on your profile picture and then click on settings. Look over to the left bottom and you will see "Promo Codes". Click on it and enter the promo code from T-Mobile and you will be good for another year, no cancellation needed. T-Mobile should not have sent the link if it wasn't going to get you to the right place and enter the code for you. They should have sent the code and instructions on how to use it.

Thank you for this. Got the YouTubeTV promotion via email a week ago and have been trying to figure out how to apply it to my current account. Their links are useless; I click on "Existing YouTube TV subscriber? Redeem Here" and it just opens up YouTube TV with no indication how to redeem the promo.