I'm not sure which department you'd have to call to get a free month of service as I didn't call Sprint back requesting anything of the sort.
Sprint gave me enough trouble just getting me another phone so I can use what I'm paying for that I won't risk calling and having an incompetent rep just screw up something on my account.
After my contract is up, I think Cingular and a Treo 750 may be in my future.