Rewards Cards

Hi,  I signed up for new service this year and got a letter in the mail for a $100 rewards card with an expiration date of 3/25/2018.  I got on line and claimed my card, since it has been a couple months and I did not receive a card I checked the status. The status said that I was disqualified because the offer had expired?? That is news to me because my letter says the expiration date is 3/25/2018. How do I fix this and get my money?? I also have DirectTV now and HBO is supposed to be free, why am I being charged for it?