Yello MTN - are you listening?

Despite requesting monthly invoices/statements from MTN the last invoice I received was dated 27 June - I have paid my own estimated amounts since then. I have now changed contracts and have requested a new invoice so that I know what amount to pay MTN at the end of this month. Three e-mails to them later and I have been told that: I should get an invoice within 2 to 24 hours, which has not happened - that my e-mail address has been loaded on to the system and that should I require an invoice I can put in a further submission (Really! Who is the customer here??) So I thought that I would try and sent off another e-mail requesting an updated invoice by the end of business yesterday. So far, no response. This is pretty sad seeing as I have been an MTN client for at least the last 35 years.