On Sprint bonuses you are ineligible if you have ever received a Sprint bonus before at any time in your life. This "policy" is not in the fine print in their offers and they will not tell you this either until months go by, the miles don't get posted, and you finally get through to a customer rep.
Nonetheless, if you are an ex-customer, they will still stuff your mailbox with mileage offers that they have no intention of honoring.