for the benefit of future searchers (since i am not alone in this): no, a publicly offered promotion does not need to be then repeated in the purchase contract, unless it is somehow unique to the specific buyer/transaction, which this was not. In fact, if you discovered later that the seller did not honor the promotion you could go back and recover it. The Customer Care calls, and the provision of service for 8 months, simply (fortunately) confirm that the promotion was indeed in effect.Customer care calls are recorded. If that happened, escalate and get them to review the recording.
But as always, what’s written and agreed to in writing is what matters, in almost all cases.