Useless ISP

Usually I don't do reviews...but this is some of the worst customer service I've received from an ISP. They don't respond to emails, ive been waiting for over 2 weeks now and not a peep. When I do phone home connect, they provide no help whatsoever, they won't refresh the line...they just won't help at all. Every evening for 6-7weeks now at 6pm onwards my 100mb up and download line becomes an 8mb download and 1mb upload...impossible to use the internet when coming home after work. Im paying R1200 for absolutely nothing...