Following AfriNIC's assumption of responsibility for IP address allocations in the African region, all pre-existing IPv6 allocations that ARIN have to be returned to ARIN, and AfriNIC will make replacement allocations.
This process is underway for TENET's IPv6 allocation. AfriNIC has allocated the prefix 2001:4200::/32 to TENET.  This replaces the allocation 2001:0548::/32, which will shortly be returned via AfriNIC to ARIN.
A a consequence, the /48 assignment to Rhodes University changes, with immediate effect, to                                                                     
Note that it is only the leading /32 prefix that changes (actually, only the 5th to the 8th hexidecimal digits change).

The effect of this isn't quite "immediate", but will happen during the course of this week. The reason for this is that we still need to get the routing for the new endpoint up and running.

Anyone who is making use of IPv6 will notice that, sometime during the course of the week, their IPv6 routing will stop working and they'll no longer be able to route to devices beyond their local subnet. Details of the exact timings of the changes aren't yet available and will likely be at very short notice (in other words, expect to see an announcement post the change).

Users who are using IPv6 router solicitation (like everyone should be) will get a router announcement with the correct prefix details. Machines listening to such announcements should reconfigure themselves. In the event that they don't, a reboot will probably solve the problem.

Users who have hard coded IPv6 addresses will need to change them.