Generally, if ecare makes a promise sprint will honor it. However, sprint can *correct* an ecare error if they so choose.
The original poster got a double-dip discount (clearly an error) - congrats and hope they honor it.
ecare is where you go when you click the contact us link from inside your sprint account page on the web... it's
ecare1@cc.sprintpcs.com (there may be more, ecare1, 2, 3?)
I generally find them to be more effective then calling in when resolving issues.