False advertising

I urgently need assistance with the next problem. I phoned axxess on promotion they advertised on Facebook for 50/25 mbps fibre line for R489 for 2 months there after 595 for 10 months. The first 2 months were honored for the amount charged, but not with the speed as promised every evening and weekends the speed is throttled to 25/0.39mbps. In month 3 the amount was billed R635 which is R140 more than the contract state. Now that I want to cancel the contract they try to trick me into paying the R499 exit fee which wasn't communicated by the agent or stated in the T&C's in the login dashboard. Thanx Wimpie