Getting less than 10% of the speed we are paying f

I have been with mweb for over 10 years now and it has been nothing but hell. We are currently paying for a 40meg line from mweb through telkom. I have been getting between 10 and 15 megs of my speed since last year december. I phone and phone and complain and all they do is pass the buck to telkom. Telkom then says there is nothing wrong with the line and so it goes on.... in total we are paying almost R3000.00 a month for an absolutly useless internet line. I can honestly say i have never been so frustrated with any service in my life!