Slow speeds are more often than not attributed to actual faults relating to your infrastructure connecting you to the nearest exchange and our data centres. This is Telkom infrastructure for ADSL, and must either be reported to Telkom on 10210, or reported to Crystal Web if we manage your line for you (i.e. you have successfully migrated your DSL line to Crystal Web).
A line fault can be caused by poor quality copper, a copper break, dry joints, port related problems at the exchange, incorrect interleaving for your connection, and many other possible problems that can only be diagnosed by a professional either from Crystal Web / Telkom (depending on who manages your line) or Telkom via their technicians for more advanced diagnostic processes.
Please note that line related faults are our responsibility to report and manage only if your line has been migrated to Crystal Web. We are unable to deal with Telkom on your behalf without a successful line migration to Crystal Web. Please also note that exchange congestion is not considered a line fault by Telkom and cannot be reported as such.
For more information about exchange congestion, please read this article - What is exchange congestion?