Being billed for a 10mbps line however not reaching speeds anywhere close!

I would never refer anyone to sign up with these guys. I had initially signed up for a 4mbps line and then upgraded to 10mbps however the maximum line speed I get in my area is 6mbps. I have logged countless faults which keep on being resolved by Telkom however my problem is not solved. Several technicians have been to my place but each with there own different excuse. I actually feel ****** by Telkom as they are charging for a service which I am not getting. CHARGE YOUR CLIENTS FOR THE SPEEDS THEY GET AND NOT THROW "THE CONTRACT AGREEMENT" IN OUR FACES.