It is correct that if you send that card back it will cost you $20 to get another "if you can get one at all". DirecTV is in the process of discontinuing service to some of the very old receivers, especially those that were not DirecTV labeled boxes (Hughes, Sony, RCA, etc.). Since DTV can do pretty much anything they like, if they want you to get a new card (or receiver) and that information gets entered into your account information you may have no other choice than to get a new card or receiver. There certainly are avenues such as speaking with supervisors or contacting the customer retention department which can be used if necessary but if a functional change happens you will likely have to move on.
Now, if DirecTV requires you to make a move to a new receiver they should provide it at no charge if you are under contract or you can buy one pretty cheap from any number of internet sources. Personally, (just me), I would not pay $20 for a new card for an old receiver, I would get a new receiver which includes a card.
What I post is my 2 cents and nothing more. Please don't read anything into my post that's not there. If you disagree, that's OK.
Can't we all just get along?