Nobody knows the answer, so nobody ever replies!

As part of my monthly debit order, a charge was deducted for many months that DID NOT reflect on my monthly invoice and nobody at Vodacom can tell me what it is for. I have raised a query about this, I have been given a reference number, and since then I have repeatedly had to call or email back to Vodacom and now nobody knows anything about the charge OR the Vodacom reference number!! I am tired of all the attempts on my side with absolutely no feedback from Vodacom - to date NOTHING and this has been queried since the beginning of October 2015. It is absolutely unacceptable - by not replying, are you assuming that this query will just go away?