Monthly subscription deduction

My email below that I have sent to Mtn on 29 May 2015<br> <br> Good day<br> <br> I've made several calls to your call centre without any success. I emailed previously regarding this issue. An amount of R685.99 was billed and I have absolutely no idea why my bill was so high. If you look at your records it will show you that I do not go over my monthly subscription amount. I was billed more than double in one month. No one has rep**** to my previous email. I am mailing because I am not getting through to your call centre. Could someone please indicate to me why my bill was so high. I would also like to set a limit on my account. It should not exceed the subscription amount. <br> <br> Please I need some explanation. <br> <br> My cell number / account ***. <br> <br> My contact number ***<br> <br> Desmene Josias