Gym company

Workers from the gym company approached me saying they have a trail till from the 18th of August up until month end.I then refused while walking away saying that I'm not interested while the worker was following me to the store I was going to and said I should wait for him so he could give me a pamphlet and reconsider my decision,I then agreed.He took long and I started walking away,he then called me and said I come and take the pamphlet, as I got there,they told me to sit and I refused.I gave them 5min of my time and said I'm leaving afterwards since I said I'm in a rush.They then explained what the company was about and how it's going to benefit me since I'm an athlete,I said I'm a student and will not be able to afford to join the gym.The worker further explained that I do not need to join but I can come for the free trail and pay month-to-month meaning,If I can afford to come,I notify the gym before hand and pay and I do not need to pay each and every month but only if I want to train. I then agreed and signed some paperwork and asked questions if something was not clear to me.I then asked for the second time that I will not be paying anything on a monthly basis unless I want to train and he said yes.I received an email the following day while I was in class and never got the chance to open it ,a few weeks later,I receive a email saying I owe the gym and then received a call days later of how the payments are going to be done.I then called them back wanting to clear this up but they said I owe the gym,I went to the company and explained what had happened and that I never joined the company.The lady who was assisting me said that I owe the gym and there is nothing she can do,I then asked to close the membership and she said it's impossible and that I should first pay for 3 months then I'll be able to close the membership. How can I pay for something that I did not take part? I received a message yesterday saying that they will be debiting this month.Please assist.