Yes so the 22d can do rain band 3 and band 38 and telkom b3. The 65d model can do telkom b3 and telkom 40 lte advanced and rain b3.
Ideally with Rain you would want a router that can do B3 fdd and B38/41 tdd and 4x4 mimo. So the B618s-22d is great for that. Although it can't aggregate both bands it can connect to 1 at a time but have the advantage of 4x4 mimo as long as you use the build in antennas. In most cases b38 gives great speeds.
With Telkom and the B618s-65d you can aggregate 2 x 2300Mhz signals so that is nice. You can also just do normal b40 with 4x4 mimo.
So it depends what network you going to main and match the router accirdingly.
As for the other networks like Vodacom, MTN and Cellc both routers will work great as they will be able to aggregate b1+b3 which the lte-a setup the rest if the networks are running.
Ideally with Rain you would want a router that can do B3 fdd and B38/41 tdd and 4x4 mimo. So the B618s-22d is great for that. Although it can't aggregate both bands it can connect to 1 at a time but have the advantage of 4x4 mimo as long as you use the build in antennas. In most cases b38 gives great speeds.
With Telkom and the B618s-65d you can aggregate 2 x 2300Mhz signals so that is nice. You can also just do normal b40 with 4x4 mimo.
So it depends what network you going to main and match the router accirdingly.
As for the other networks like Vodacom, MTN and Cellc both routers will work great as they will be able to aggregate b1+b3 which the lte-a setup the rest if the networks are running.