Overcharged on account and no itemized billing statements

I have requested 3 month's worth of itemized billing as I need to check what MTN is charging me for as I keep on being overcharged by R300 on my monthly bill. I have logged a request almost 2 months ago and have escalated 3 times already as I have still not received these itemized billing statements but they have conveniently charged me for them already! Every time I call them they tell me they have sent it from the system but I keep telling them I have not received anything! They keep confirming my email address and it is right! Why is this so difficult! You overcharge my bill and when I try to investigate you disable the only way for me to investigate! Call me to get this sorted once and for all MTN! Your service sucks!!!