having to pay for something i don't use

I was told on 21/08/2014 that there was 20 GB data was load and I called on 7 /10/2014 to be remove and put and R50 limit. I fully understand that and take responsibility but I was told on 09/12/2014 the 20 GB was activated again and the best explanation they gave me is that I push a button. After what happen in August 2014 I would never knowingly active the 20 GB again now they want me to pay for something I haven't use. There is a contract that can upgrade now and other later this here but with what happen I'm reconsider it. This is the second time i have put in the same complain i have been contact twice by the agents and both time they told me that the case will be investigated. But it ends there no 1 have contact me after words the last person i spoke to was Blanch Opperman