Worst Service

It has been about 3 weeks that I have been phoning regarding our internet speed that drops every night between 19h00 and 22h00. The servicd that I have received from them is the worst ever. They have "apparently" logged the issue and said someone will phone me back. Till date no one has phoned back or sorted the issue out. Every time I phone I am put on hold for 25min + and still there we are no closer to sorting the issue out. I am put through from one person to the next. Worst service that I have received from Supersonic.