I know that they used to give no refunds on any programming that has already been paid but sometimes they will send a check to you for the amount. Sometimes there is a delay in receiving that check from them though so I would expect there to be problems when trying to get the refund from what I have heard from others in the past.
Well in my case I had annual AT150 and the Mega Movie Package, I changed it to the AEP. I did it 3 weeks early (they do not seem to have the ability to do changes in the future, i.e. when your subscription is to renew) and they ended up prorating back the 3 weeks of the annual prepaid and converted me to the AEP.
If you do prepay for one year then have it dropped to a monthly basis before the year is up then they will go back and charge you monthly for all of those months. For example, you paid for a year of AT180 in which you get charged for only 11 months instead of 12 and 11 months go by and you decide to go monthly. You will get back NOTHING (because someone would have to not be thinking if they go this route). If 10 months go by you will get back 1 month, 9 months go by you get 2 months back, etc.
They do not have to return your money but their is a option for you to transfer your account to another person in their residential agreement. I still have Dish Network service till July 31 and I signed up for DirecTV with 3 DirecTivos and one standard receiver and I will buy the HD DirecTivo as soon as its released. I should have waited till DirecTV launched their new satellite for my locals but hopefully it will not be to much longer. I sold my Dish Network 6000 HD receiver for $375 profit so it kinda makes up for them not wanting to give me a credit back on the programming and I just watch Dish Network for the superstations now and DirecTV for everything else.