If they inspected the phone and gave you a proof of $200 credit on that order date, then they will probably honor it. They gave me that $200 credit for my AT&T iPhone 4 mistakenly for my Note 4 pre-order; it's supposed to be for a new iPhone purchase. It even had a 3rd party back cover. At the time of actually trading it in they were like we don't care it's the manager's fault for approving it back when they did it. They honored it even after my pre-order was cancelled (by AT&T, not me).