Cell C who is steeling.

My son raised an issue where every time airtime or data is loaded on his pre-paid account that the airtime / data just disappears. This has gone on for quite some time now and starting to get fed up with this issue. Cell C keeps on deducting his airtime because of unknown reasons and therefore would like to have any Cell C agent / personnel contact me to explain why this is happening. Firstly, the airtime which is paid for cannot just disappear without any reason, you are a big company and therefore do not need to steel. Please contact me regarding this issue so we can resolve this matter asap.