Telkom's provides service they can't deliver on

Telkom last month upgraded my wife's account from a 4meg adsl line to a 10meg adsl line. But a week after the upgrade I noticed that my speed is still capped at around 4.3 meg. After phoning Telkom I was informed that we're not close enough to the exchange and therefore we'll not get more than 6.66 mps. But like I said, we're not even getting that. The problem persists after I logged two faults. But recently was advised by a Telkom employee that I have to log a dispute because basically I was **** to by the sales people when I was upgraded. His advise was that I downgrade and log a billing dispute to get reimbursed for the extra money I paid on my account. But surely this constitutes something akin to *****/false advertising seeing that this is happening to a lot of customers according to this employee? I'm still waiting for someone from Telkom to rectify this problem and to contact me to downgrade back to 4 meg.