20mb vdsl line only syncing at 2.7mb

I am subscribed to a 20mb vdsl line, but since 12/12/2015 the line is only syncing at 2.7mb.<br> So I have been experiencing extremely slow connection for more than a month now, where when the fault was logged I was promised it would be sorted out in 7 working days.<br> I am paying for something that I am not getting.<br> I've been speaking to the help desk every 3-4 days and being promised that somebody will get back to me which never happens.<br> Telkom technician has been out and said that he can't find the fault?<br> Please give urgent feedback.