Vodacom Fibre billing

I was overcharged in December. After complaing on hellopeter Vodacom resolved my matter and credited my account with the amount overcharged. In January they deducted R946 instead of R750 . This was before they had resolved my December matter. After crediting my Vodacom account they continued to charge me more than R400 again for January which i had already paid instead of just billing me for February onwards and crediting back the overcharge for January. I am tired of calling because since i called to query this on the 8th of February no one has called me back. When i called the people i spoke to were clueless and couldn't help me. It seems like whoever is doing the billing there has no clue as to what they are doing. Please Vodacom employ people who know what they are doing.