I think it's worth adding that the BOGO deals only apply to customers adding a NEW line. If you are an existing customer such as my wife and I, you do not get the BOGO deal if you are trying to upgrade (like we are from the Note 5). Simply put, they value only new customers, not existing ones. So take that into consideration when all of these places float the, "Whoa, AND they give you a BOGO discount".
last year I did a BOGO with T-Mobile. We added the line as existing customers. After we received the card for the price of the free handset, we paid it off and closed the line. That is the only way that I have seen a BOGO work for legacy customers.
Unfortunately, T-Mobile no longer sends cash cards. The funds are spread out over 24 bill cycles as credits. So, you have to keep that line you added to get the BOGO deal for two years. With no more kickback offered, you're spending at least $480 to get $720.