Samsung Galaxy S6/S6 edge buyers on T-Mobile will get a free memory boost from 6/24 to 6/27
In other words, while the promotion is in effect, you can purchase the 64GB version of the Samsung Galaxy S6 or Samsung Galaxy S6 edge for the price of the 32GB model. That will save you a total of $80 and you will be able to take home the device putting $0 down, paying off the balance in monthly installments (assuming you're well qualified, of course).
If you need more internal storage (remember, there is no microSD slot on either handset), the 128GB Galaxy S6/Galaxy S6 edge can be bought for the price of the 64GB model thus saving you $100. If qualified, you can put $99 down and pay off the balance in monthly installments.
The deal is available from T-Mobile's online or brick and mortar stores. And to reiterate, to take advantage of the free memory bump, you need to make your Galaxy S6 or Galaxy S6 edge purchase no earlier than this Wednesday (June 24th) and no later than this Saturday (June 27th).