Hard to cancel promotional services

I signed up for DirectTV almost 3 months ago and got a promotional package of Cinimax, HBO, Stars, etc for 3 months. Tried to cancel today (about a week before expiration of the package). Explained to one agent; was placed on hold; explained exactly same information to second agent who said "you have to call back on the day it expires...we can't cancel it in advance. There's no way to do that."

Now I have to go through the whole process again....about a 30 minute endeavor counting the time waiting on hold. What poor customer service!