This is from legal.hughesnet.com:
If you cancel after activation but before the end of your 24-month term commitment, you will be charged a Service Termination Fee of up to $400. The exact amount of the Service Termination Fee will be $400 for the first ninety (90) days after activation of the HughesNet Service. Thereafter, the amount will decrease by $15 per month for each month of active Service.
If your service is new enough, your sales call may still be available for the Hughesnet staff to retrieve and listen to, so they can verify what the sales agent told you. If you were misled by the sales agent, you may be able to get a reduced ETF.
The Hughesnet reps will be back on tomorrow (Tuesday).
Edit: If you leased your equipment , you need to return your HughesNet modem, power supply, and radio in good condition within 45 days of cancellation date or be charged a $300 Unreturned Equipment Fee ($100 for the modem and power supply and $200 for the radio transmitter).