Failure to attach invoices to the statement.

Account no.I ********** -2 Dear Vodacom, I'm writing to you to quiry the statement that you are sending me monthly without all supporting invoices. On my statement,there are two invoices charged; Invoice H7-DYQZC & H7-E3SV7. The first invoice to the amount of R757.66is attached, yet the other is not. I find it grossly unfair that I pay an amount that is not substantiated. How do you charge me for an invoice I haven't seen or confirmed? Every month I have to phone and ask for a copy of the invoice you've left out. This is done at a great inconvenience as your customer care telephone quee is always the longest in all companies I deal with. KINDLY ATTACH ALL RELEVANT INVOICES ON MY STATEMENT SO THAT I CAN SEEE WHAT I AM PAYING FOR.