There is a thread on the Telkom community dealing with ASSIA. Unfortunately, there are no credible Telkom comments on the thread. The responses are a mixture fact and fiction, good and bad advice and total BS.
Suffice to say that most people are very upset that a user cannot easily CHOOSE to be connected through ASSIA. There are many of us that have excellent line infrastructure or a very close to the exchange or DSLAM node who get zero benefit from ASSIA.
Generally it appears that most experience an added latency of about 15 to 30 ms because of the interleaving technique used by ASSIA.
If OP subtracts 30ms from his ping results then his latency drops to below 200 ms which is well within range of expected results, until he tells us exactly where he is and then posts the ping plotter results so that we can check on any other possible issues that may exist affecting his results.