Under section 604 of the FCRA, a business may do a credit pull if they have "a legitimate busness need for the information in connection with a business transaction that is initiated by the consumer." Applying for DirectTV service is a business transaction that is initiated by the consumer, so their right to do a hard pull is not in question. The only question is how they code the inquiry when they make it. That decision is entirely up to them, provided they made no prior commitment to you to code it as a soft inquiry. Get that commitment from them in advance if you have not yet applied.
If it has already reported as a hard inq, contact them nicely and ask if they can please change their report coding. They have no legal obligation to do such.