Refund of premiums after cancelation

I canceled my contract in 2019 November and to my surprise I have been debited monthly since then. I called and demanded refund and was told the contract I has was valid for 24months and according to me it was only for 12 months renewable after that and I opted for cancelation. At the time of my cancelation they couldn't prove to me that the contract was valid for 24 months. Planet fitness has been *****ing from me and I want my money back.