No Internet conectivity after 7pm

Everynight after I come back from work, my internet is extremely slow. First logical thing to do is to restart the modem. <br> <br> After restarting the modem, my internet cuts out completely and have to wait an average of 4 hours before it turns back on. I still manage to connect to the exchange, but from there I receive nothing. Tried multiple ISP'S, baught a new modem, phoned my ISP, they say everything is working on their side.<br> <br> Tried contacting Telkom during the day as I sit on hold in the evengs using 10210 and can't get through. They couldn't resolve the issue as they don't know whats wrong. <br> <br> I logged another fault, waiting for them to call me back and arrange a call out.<br> <br> This problem has been presisting for more than a month and a half now.<br> <br> Extremely frustraiting and bad quality of ADSL service.