Billing nightmare

The worst mistake of my life was ever joining this company. Last year March I changed my banking details and I went to them to let them know of this and gave them my new banking details to change on their system two weeks later da debit had to go off on the new account but it didn't but I had mad provisions for incase they haven't changed so they can still get money from my old account but they didn't debit that account either. I went back and they said they had lost the bankin details fine I gave it to them again and the following month it went of I asked them to debit for both months but they didn't. Fine so they started debuting the regular 199 and odd amount like 99 rand or 58 rands so I called in and asked them y don't they debit the full amount that I owe them they said they but they never did they continued to debit the odd amount until last month when the debit the 199 and 200 ok that's fine and it wasn't a problem but than today I go to they gym and they tell me I have an outstanding balance of 248 and I asked their response was so dumb they told me that when u have an outstanding balance you have to pay it in cash so I asked why have you debiting extra and no response