Too bad this wasn't explained to you. Any kind of on-demand video burns up a lot of data. DIRECTV On Demand especially, will consume your data in a hurry because it's streaming it in full HD. For this reason as a courtesy, we won't connect our customers' DIRECTV receivers to HughesNet without first explaining the potential problem.
Hopefully, you have another Internet service available in your area. Many people do not. No doubt, AT&T Uverse is not available at your address, or else the DIRECTV sales person would have offered that first instead of HughesNet.