DSL line rental is not separate as far as I know. How fast is your line? Mine is 384k.
EDIT: Mine is also R114.91 by the way.
The DSL line rental is separate.
You always have to pay Telkom for the voice portion and the amount will depend on whether it is a plain voice line only or whether it is part of a special package.
You may order your DSL line directly from Telkom or from one of the ISPs that offer DSL lines. If you use a non-Telkom ISP then they will bill you separately for the DSL line rental and any data usage. If you use Telkom, then it will appear on your Telkom bill as a separare entity to the voice rental.
You can get your DSL line from Telkom but buy your bandwidth data from another ISP. In this case, Telkom will only bill you for the line rental, and not for any data usage.
In your case, it seems that your ISP ordered the DSL line and is billing you for it. You first need to transfer the DSL line to Telkom before you cancel the contract with your ISP. When the transfer is complete, you can then buy the bandwidth data from Afrihost. Unfortunately, Afrihost do not offer DSL line rental services, so you will need to revert back to Telkom or find another ISP that does line rentals, eg WebAfrica.
Telkom offer a very attractive package of 384 DSL line + 3GB international bandwidth + 20GB local bandwidth for R258 p.m. Add the R87 from Afrihost for an additional 3GB of international bandwidth, and you have enough data for the average user.