Complaint - Contract

I have a 2 Meg ADSL contract with Telkom, which includes uncapped data. Every month from about the third week of the month our Internet slows down to such an extent that we can hardly do anything. I've contacted the Telkom Technical Help Desk on many occasions for the same problem and every time they inform me that our line is on Soft Cap due to a \Fair Usage Policy "which they have in place. This does not make any sense because my line is uncapped which means no limit. I have contacted them again this month about the same problem but nothing has changed. My Telkom number is ***"""