AFAIK, HughesNet does not have a "$50 VISA Gift Card" offer. Some independent HughesNet Retailers may offer this but it's not sponsored by HughesNet.
There is a $50 discount offered in some areas. Until June 30, it was offered as an instant $50 discount off the first month of service. On July 01, it became a $50 rebate after the first 90 days of service, again offered only in some areas.
How, when and where did you order your HughesNet service?
I just listened to your sales call and hear that you were quoted for the $50 cash back promotion (a check in the mail) after your 2nd month of service. Have you not received anything in the mail regarding that? Hoping we can get this straightened out.