Cancelation of contract

I just recently joined zone fitness.. Right after signing the contract I went back to the gym to cancel after 3 days of signing and the desk lady didn't let me cancel the gym contract but instead she insisted that I should give it time and now when I still insist on canceling they telling me of paying 60% of the amount or else I should just make time for the gym though I've stated out that I don't have the time because of work.. I find myself working away from Pretoria 90% of the time.. Now am busy paying the gym I don't even use.. So heart broken