Your bill can go up due to a discount ending. You can have credits and charges, and vice versa, if something changed with your service. You can sign into the HughesNet My Account site, click on the My Bill tab, then click on an invoice in your Invoice History to view it. You can then scroll down and click on the individual charges to see a breakdown.
I'm sure a rep will reply. They're on M-F from approximately 8AM to 5PM EST. They usually reply within a day or two.