None Cancelled Contract

So there was a gym contract in 2016 with one of Planet fitness consultants, of which when i took the contract the consultant advised me that it will be on a trial basis which i can cancel whenever i want within 3 months by just telling him. Which i did and stopped going to the gym, was then shocked when i received calls that i owe Planet fitness about R11000. I am shocked how you guys really want to regain your profits in this manner. How can i owe you guys when i instructed the person who i dealt with to cancel and the person did their own thing? Can someone please sort this out as its gonna affect my credit record.