I did get a double credit promo in Jan (out of Chicago) and got 4 credits (for two one-way trip). Othewise, I would have receive 3 credits (including 0.5 credit for each one-way online booking). Can this doule credit promo be combined with online booking promo?

As far as double promo details (terms and conditions), there is no limitation (like cannot combined with any other offer). I checked the customer service and they said no (just 4 credits) but they did not explain why I cannot combine the double credit promo with online booking promo?

If anyone took this double credit prmo, please let me know. Thanks.