If you honored the terms of the agreement and cancelled in the appropriate  way within the appropriate time frame, you would not be responsible for the charges. You are only responsible  under an agreement for costs, charges, etc. in compliance with its terms. You should check the agreement very carefully, however, to see if  you actually did cancel in the proper way. For example, if it required that you cancel in writing by mail (e.g. mailing something to a certain address) and you only tried to cancel by phone and by email, then your cancellation would be ineffective. So double check all agreements, paperwork, etc. to make sure you did in fact comply with its terms, including terms of cancellation.