Honestly, what did you expect? .. it's Telkom.
I got the kids the 10gb/month package from 8ta and though they were happy last year this year its getting worse by the day. Signal's fine there's just no throughput at times, and those times are getting lengthier and more frequent.
I have the same problem on ADSL incidently. Telkom's talking about pie in the sky FTTH & 40mbps ADSL while I just logged a dispute demanding a refund 'cos since Jan they're barely delivering 1mbps while I'm paying for 4.
Seriously, as far as Telkom goes lower your expectations else you're just going to be disappointed.