ADSL speed

Have been trying to get an answer out of Telkom for weeks now.<br> Our ADSL exchange is capable of 20mbps data rates yet the whole area is only on 4mbps. How in this day and age is this even still an issue. For weeks now not a single person at Telkom can give me a answer or even tell me when and if ever they will allow us to use these speeds.<br> <br> Surely someone should have an idea when they will upgrade lines if the exchange already is well above the slow 4mbps we are currently stuck with.<br> Business these days can simply not function on only these low speeds.<br> <br> Please can someone try and explain this to me.<br> The 10mbps has been enabled on this exchange for well over a year already yet we are still stuck on the 4mbps.