DES****ANCY ON MY ACCOUNT BY ZONE FITNESS

I took gym contract for six months with Zone Fitness last year 2023..i gave Zone Fitness authority to debit the monthly payment on my account on the 15 of each month, but they refused saying their policy is allowing the 1st of each month debit I accepted the deductions of the 1st. What surprising me is that if they got insufficient funds from my account they debit me on the 15 of that particular moth, what is frustrating me is that I've never reverse the payments I didn't complain a bout that I completed the six month contract but they still debiting me and I'm not attending the gym but still zone fitness is sending me messages of outstanding payments, I'm receiving calls from them about the outstanding amount which is going to continue until I go to the branch to cancel, I was there to get it canceled the lady assisted me said she canceled it on the system. How can Zone Fitness do this to me , des****ancy on my account, continuing *****ing my money telling me I should have read the terms and condition written on the contract forms, what if I can't read and write or they don't accommodate uneducated people? I ask them to take me to court or list me with credit bureau