Automatically increased my usage limit after I set it

<p>Around April time I set the usage limit for my cellphone contract to a R1000 (included the standard monthly charge) after receiving two very expensive bills. Everything was good after that, even received the "you have incurred 90% of your usage limit" notification. So I recieved my satement for this month to the tune of a R1100, a full R100 over my usage limit. I did not once recieve a notification during the billing cycle informing me that I have reached 90% of my usage limit. So I investigated by logging on to the self service portal. Checked my usage limit only to see it has "magically" increased to R1548.29. </p> <p> </p> <p>Now this number is definitely not human input, too precise for that. I logged a call with MTN this morning, kuddo's to the call centre attendend for the professional reception and assistance, even though this is a matter for the billing department.</p> <p> </p> <p>My question is firstly, how will I be reimbursed for this, I was not approached for consent on increasing my limit and this was done without my knowledge (no notification was issued to me)? Secondly, how can I be certain this will not happen again in future?</p>