Dishnetwork rebate never issued!!!!

I have been given an offer for two rebates of each of $100 last year in August when I upgrade the satellite service to HDTV. One upgrade for $100 for the HD programming of $10 for 10 month, and one time credit of $100 for 'dish'n it up'. I received the 10 month $10 upgrade each month, but I have been calling ever since on a regular basis for the one time upgrade. Nothing happenend so far! I have been promised on every phone call by supervisors, agents etc...to receive it soon, few weeks, up to 6 weeks etc. Today, I called again, and I got interrupted and shut off by the service agent that was so rude and just explained I wouldn't get the credit since I received one already and that is it and she hung up! This is the most rude thing of all! I am not giving up,, or cancel my service all the way at this point!!