Not getting what you are paying for

I am a Telkom ADSL customer - I am paying for a 4MB uncapped line and have been paying since May 2014. I have yet to experience 4MB! The line speed is decent (WHEN LUCKY 2MB to 3 MB) between 08:00 till around 14:00. After 17:00 and weekends I have around 0.5megabits.<br> When I report the matter I am each time switched to a different \port"which addresses the issue for a couple of hours and then we are back to the problem. I have reported the matter on numerous occasions. All I get is that the matter would be escalated but it is not being resolved. <br> Telkom collects my money for a 4MB line monthly yet I am not getting what I pay for and my issue is not getting resolved. I need the matter sorted once and for all and insist on a refund"""