Out of SA, but data usage still rolls on......

My wife and I were in Zambia last week and imagine my surprise on our return, when I looked at the data usage shown on my contract.<br> OK, MTN state that this is not the accurate amount of data, but still, how can ANY usage be recorded when I am not even able to connect to their system?<br> Last year when we returned from 6 weeks in Australia, I reported the same problem. I have never received a believable reply.<br> Even now, MTN want me to phone some one to get the response. No way, I use E mail so that I have a record of such interactions.<br> I would be grateful if MTN could shed some light on the matter.