Make sure you have that letter in front of you when you call. I got the same letter a while back. Made the phone call and the rep started quoting what is was going to cost. I finally read the entire letter to her.
Now for the warning. If you have any SD receivers they will have to be switched out for HD receivers. If you have just 1 receiver no big deal. I had 4 receivers, 2 HD for my HD TV's(VIP612's), 2 SD(510's) for my non HD TV's. The rep on the phone said there would be no problem, they would just need to install new dish. Installer arrived and what he was going to do was not was discussed on the phone. Installer called Dish and put them on speaker phone. Dish rep basically told me I had no choice and came across with a snotty attitude. I refused her only solution and the installer left after I apologized for wasting his time.
After getting more notices of the urgent need for an equipment upgrade I called Dish again.I explained my current setup and that my requirements was to have 4 DVR receivers. Rep said no problem. Appointment made. Wrong, installer arrived, said the SD receivers will not work after the dish install. Not only that, I was then informed that they were taking back the 2 SD receivers, 1 which I had about 100 hours DVR'd on it. He explained that if I owned the receivers then they did not need go back. He ran the receiver #s and fortunately the 100hr worth of DVR program one I owned.
Installer had a 622 on the truck and that is what he switched out for the 2 SD receivers. And the reason I wanted 4 receivers came to pass within the hour after the installer left. Son was arguing with me because a conflicting DVR recording time. So I don't use the 622 at all to record now.
So what I am saying is to make sure what the Dish rep tells you can actually happen. I have been a Dish customer since 1998. I have always dealt directly with Dish. But the last 2-3 years I have been at a 50-50 ratio of knowledgeable/friendly reps or "I don't have a clue" /snotty attitude reps. Hopefully you will get the knowledgeable/friendly rep.