Not responding to service request

Since December 2015 I have logged several service requests to Telkom, received reference numbers via sms's, and then....nothing. No one bothers to contact me or to resolve the problem. <br> The actual problem is that I subscribe to a 40 Mbps VDSL service which has been working great for about 2 years until December last year. Since then I get between 0 and 15 Mbps. There is obviously either a physical fault (I am within 250 metres of the dslam) or a software issue.<br>