Telkom are you *****ing my Data / My data is disappearing

My data is disappearing and I live alone so can Telkom please answer a phone and stop with all this automated nonsense that does not address the issue and explain where my data is going to. I have disconnected all my devices from my modem and still data is being used! Telkom offers 'amazing' data deals and appears to be *****ing the data back so there is no amazing deal actually. I went to Telkom Musgrave for assistance and was assisted by a rude employee who started lecturing me on how I should speak to her. She eventually assisted in logging a call and i was contacted by a call centre agent who kept me on the phone for ages, telling me that I had used the data because the system says so. 50G in 3 weeks. I have 29G data in my phone and have never run out and I use it all the time. Can I cancel a contract that is less than a month old?