Review Cancelled my beneficieries contract after two months

In August 2019 i signed up a contract at Planet fitness in Brakpan.The sales lady gave me and my sister's daughter a special offer as it was a women's day special.I signed the contract and was informed that my sister daughter could gym with me under the same contract.She was even given a tag.Two months into our contract she was blocked and i was told we have to renew her contract as her contract expires.I demanded to speak to the manager and he told me its the companies policy that she have to be my daughter to enable her to gym under my contract otherwise she have to sign up a new contract.I told him that the sales lady was fully aware that she was not my daughter when we signed the contract two months prior and she did not mention that its against the companies policy.He also said she is off sick and can't defend herself.I said then i want to cancel the contract as this is not what i signed up for.He coldly told me to phone in to cancel my contract if i wanted to and also informed me that i will be liable for the cancellation cost.I am very dissapointed in the way the matter was handled by the manager and i feel i was tricked into signing a contract.Why was i only informed two months after the contract was signed.I urgently need someone to investigate and give me feedback regarding this matter