Basically Telkom doesn't want to peer with MWeb for free so they're not going to let IS just fetch all their content and give it to MWeb clients for free either, and visa versa. IS would pick up the costs of transmitting the data from Telkom to themselves, so they wouldn't do this for clients who aren't even paying them (this is from an MWeb user's perspective).
In your case (Telkom user), I suppose Telkom could probably do this if they wanted too but MWeb might then block the traffic. They would also need IS to allow them to do this, peering only works with the content actually hosted by an ISP, so peering with IS only gives you access to their network not external networks they connect too. (Pretty much all a slightly educated guess from the recent threads on peering)
Also if ISPs could use peering links that don't belong to them to get through to all other networks then there would be no incentive to peer directly.
