Dissatisfied

Worst thing about netstar is the clause that if you cancel contract with them you must pay for the remaining months. How does a person pay for a unit he's not using? Cancellation means termination of all that was agreed upon in the contract so why after cancellation netstar still wants to collect money for the period I didn't use their unit ? And the worst thing is I took out a new contract with them but they still want payment for the one I cancelled! I have two contracts with netstar now but they still insist on collecting money for the cancelled contract. Is it greed or no care for clients ?