Everyone's using Costco for their upgrades right?

Hey all, everyone’s going through Costco for their T-Mobile upgrades right? Seems like a no brainer with the upgrade fee waived and the $100 Costco Shop Card. Also just found out you don’t have to use a Visa even though it’s Costco since you’re actually paying T-Mobile. One tip someone gave me, apparently the Costco site can be a little buggy so build the upgrade in T-Life first and leave it in your cart, then go through Costco and it should already be there ready to check out.