Query on unauthorised items on my account

I have a 3G contract with Vodacom which I've had since 2009 which I use for work purpose. The contract initial agreement was R99.00 which was increased this year to R109.00. In September 2015 I received a statement with an amout of R808.00 this amount was made up of Airtime Subs R306.14, 24 months Handset installment of R402.63 plus VAT R99.23 and NO 3G amount. I immediately contacted the customer contact centre to advise that I had not authorised any upgrade on my account and wanted to know who had made this request. They logged a query (ref no.S3-8IH3J-JT8N9) and advised that someone will get back to me within 48 hours,this call was logged on the 1st Oct. After not receiving any feedback as promised I called Vodacom again on the 19th Nov to find out the status of the query and was informed that they were waiting for an affidavit and copy of my ID in order to continue with the investigation, these documents were them submitted. After again not receiving any feedback I called Vodacom again on the 1st Dec and was transfered from one dept to another until the line got cut off. To date no one has had the decency to update me, instead I got a bill of R2800 and a rude call from accounts