poor services

I cancelled one-to-one contract and pay my account to the cent, there was cancellation fee which I was told to pay but the didn't specify when to pay, how can they be so ***********. now they want me to pay 2 times the amount. they are telling me about the collection fees that were not explained. even the cancellation fees it was something new I was not told when joining that contract. this is bad service, poor selling s****s.