DirecTV DirecTV Stole $500 form my account Nationwide

What you don't understand is that your friend signed a contract. That required a Credit Card to sign up with and just in case of breech of contract. since you were not the one who signed the contract with Directv. Then they don't have to notify you of anything. But they were required to notify your friend 15 days before they charged the Credit Card.

If your friend had found a Independent Dealer who to tell the truth. Myself I would have declined to do the the job and still would have  explained why it was a bad idea to use someone else Credit Card. But you will find that customers, Dealers, Dish and Directv don't care about anything but themselves. 

So no matter what your friend should have contacted you once they decided to stop paying their Directv bill. Next time tell your friends to go to Walmart and get a Prepaid Credit Card. This would save everyone a lot of headaches and from screwing a friend in the process. 

If they are really a true friend, then they would pay you what you lost.