Being billed after account closed

After much trouble, I was finally able to get Telkom to close my account, something their own employees said should take only a few minutes, but wasted days and days of my time. After receiving telephonic confirmation that 22 May is the last day of internet service and that my account was officially cancelled, I have now received a mail stating that Telkom is debiting a certain amount from my account on 5 July for internet provided in June. I moved house on 20 May and since 21 May I am not even living in the same province. I find this situation to be ridiculous and incredibly hopeless. What is even worse, is that there is nothing I can do but try to continue to ask Telkom to cancel everything. From the very first day of line installation when their agent wasted my day by waiting for hours outside my apartment, but not pressing my doorbell or phoning me to tell me that he has arrived(I was inside waiting for him the whole time)