Incorrect debit amount

<p>For 6 months I had no issues with yellodata, then on the 1st July they decided to spoil our relationship by debiting R454 instead of R59, I called the cc and the agent told that I used 300mb over my limit in April sometime, it costs 99c per megabyte is what she said but this still does not add up to R400, she just asked me if there's anything else she can help me with, but she can't sort out my problem, I then asked her to cancel my yellodata permanently, I was sent the below message not long after I hing up, </p> <p>As per your request, your YelloData order MP- ********** 5-1 has been cancelled. We're sorry to see you go! If you have any queries contact us on ********** 550</p>