Lack of concern over billing issues

It actually pains me to have to go this route to try and get clarity on my queries but emails to the club have mostly gone unattended. I got one response and after several more emails to them, nothing. I joined Planet Fitness last year and paid 1 year upfront via Edgars. I was then going to pay R399 once the 1 year was up. The first deduction came off and it was R423. Now it may not seem like much but it is the principal, how can they just debit more without my consent? Honestly, in today's competitive market, one cannot afford to lose customers but Planet Fitness obviously don't care. So, if you don't want to assist me then I am just going to go somewhere else. Please can someone contact me to sort out this debit. I now received a one liner telling me it's an increase. I signed this contract last year, should I not then be charged what the price was at the time of signing? This is a minor query but they way they have handled it is shocking and not what I expect. Don't want to be part of this gym.