Bad service and empty promises to get back to me

They deducted R1100 instead on R400 which I had to reverse. They said they will resolve this matter I never heard from them again. I wrote an email when they deducted the amount that we didn’t agree on again and they said it was resolved of it wasn’t. They could not explain why I was over charged. They refused /revoked access to the gym. So I said i won’t pay for those months as it was thier fault for deducting the wrong amount which I had to reverse. They refused to share my phone conversation which they had agreed to get back to me and never did. Till today I don’t know why I was over charged. I stopped going to the gym because of thier mistake but they still want me to pay for those months.