Capping your uncapped adsl

I have uncapped internet for a few years now. But for the last couple of months Telkom have been capping my uncapped internet???? I was told that I am using too much Internet and they are not cutting me off just slowing my speed down. I pay extra every month to have faster internet and get slowed down to such a pace that I cannot even receive emails. This happens every month for at least the last week and a half before end of month and if you complain no use because if you dont accept you stay cut off till end of month. They force you to comply.I have resorted to using Vodacom to read my emails the last week of the month. Bunch of *****s holding you ransom.