paying for something i do not have

hi all please help with how i move forward. Last year I took out a contract with this company. I received the device and indicated that I do not want to continue with the contract. I sent an email upon receipt that I was not interested in the type of device. I then got no response to my mails and eventually figured out which number to call. I was then told there would be a cancellation fee which i agreed to. A day later i received a call stating that my cancellation was received and that the device would be collected and i would have to pay one month's installment. Which i agreed to the device was then collected and then my account was debited however i have been debited now for almost a year with follow ups and to no assistance i have raised the matter with no help. Today called to resolve this since i did not pay this month's installment and i was told they could process a cancellation fee or continue a monthly installment. I do not understand how i must continue to pay for something that i do not have or pay a cancellation fee if i was told something different

Does anyone have advise