To understand the exchange issue a little better, here is how it works in simplistic terms:
Your line______________Exchange____________IPC_____________ISP Network____________Internet
The last three go hand in hand but all are needed to gain access to the net.
An ISP must have a registered IP range issued by AfriNIC. This range is then populated across the Telkom exchanges around South Africa so that Telkom know how and where to route the data for which ISPs. It moves over their network from there, over to the closest point an ISP has purchased IPC capacity at. It then moves over on to the ISP's network. So really what exists at the exchanges is all of Telkom's routing infrastructure - there's no ISP routing infrastructure there.
I understand the frustration when exchange issues crop up - I really do. About 50% of our support queries are actually us diagnosing a Telkom fault on their behalf. We then bear the brunt of customers getting very angry with us when we state as such. It's exacerbated when a customer switches ISPs and the packet loss disappears. But this doesn't mean the ISP has done anything there - the ISP simply cannot. We don't have facilities leasing to install infrastructure inside Telkom's exchanges - ISPs install their hardware much further down the route at a peering point for IPC. Also remember that an exchange isn't the little box up the road from you - it's a rather large building housing massive amounts of equipment. Each piece of equipment does something different, and each piece of equipment must be fully operational for the network to run smoothly across all ISPs. If one piece of hardware fails or is not working 100%, it can result in packet loss on one ISP's account and not the other, perhaps. Again, we can't test this, nor do we get any data about this from Telkom, so this remains an educated guess.
Here is a pic of a Telkom exchange, for some context:
Now imagine a single loose cable there. Or a single faulty port. Or router. Or configuration. etc. And you start to imagine the complexities of the situation. I hope this helps to explain why we can't fix, diagnose, nor answer exchange congestion for you, irrespective of the results showing no packet loss on one ISP or another.
BUT, you MUST report it to Telkom still. You absolutely have to. if you don't, the problems will 1) persist, and 2) may get worse and end up spreading to all of your ISP accounts. ISPs (including Telkom) rely on customers reporting faults. We can do a lot of stuff behind the scenes to monitor, and Telkom have bettered their reporting and management of this over the years, but they still rely on your calls and fault reports to them, in order to fix the problems. If they don't know an issue exists, how are they to fix it? You cannot assume that they are monitoring your specific connection at all times.