Overcharge and no response to dispute logged

I went to a Telkom shop to pick up a LIT box which was free as part of the ADSL line package I ordered. On April 13 I logged a dispute as I was charged for the box that I should have received for free. Not only was the issue not resolved, but in May I was charged over R1000 again. I have followed up on numerous occasions and each time was told that the dispute is still open and that they will escalate. I am at my wits end and fear that I will be charged again. I am already overcharged by about R 1800.