Overcharging, now can't find references from their own system

I signed up for a "Black Friday" deal in November 2018. The very next month Vodacom tried to overcharge me (apparently CLIP charges aren't included in their specials which state TOTAL ). After getting them to fix this, I have noticed that they have been charging me again for this. Firstly, they tried to BS me that there was an increase (they tried this before their increase) Secondly, I sent them the reference numbers where these issues were "resolved" and apparently they can't find them - why give a reference number if it doesn't do anything???