Sercvice/Call Centre

I've been experiencing problems with my ADSL for about a month now. At first the line would go down intermittently. I logged a call and Telkom said all was ok from their side. The problem persisted and I was told that the modem might be causing the problem. I bought a new router but the problem still persisted. I then called in and was told that they don't want to send a technician through because everything is ok on their side so they're scared I might get charged. First of all I do not have a problem paying if the problem was rectified, what I do have a problem with is paying for something that does not work. I'm on the verge of cancelling my subscription, I've really had enough of this terrible service.