Cancelled Contract Telephonically yet now i'm owing them -Day Light *******

I asked them to cancel my contract as I had an injury in 2014 at the Gym while using their equipment’s of which it was faulty and regarding their cancellation process I was also advised that there will be no cancellation fee; I had to pay my own medical bills and when I requested to cancel I told them this and was advised they will cancel it, out of the blue in 2018 I now owe them and they still harassing me with calls. honestly this is day light *******