Cancel of contract

How can they penalize you if you do not cancel your contact 30 days in advance, because I cancelled late I must now pay for another 90 days. This is not fair no other company works like this. They should be happy that I have already paid them 2 months more then what I should have because I forgot to cancel my contact but no now I must pay another 3 months.

This is totally not on!!!!!!!!!!!!!!!