Made a switch from Telecom to Slingshot telephone service long time ago. Had an ongoing issue for more than a year with a quality of the phone/adsl connection. Re-soldered all internal house phone sockets, removed capacitors, but had no luck. Suspected the bad cable from my house to the exchange. Rung to the Slingshot Help Desk 4 times during the last year. Everytime was scared to death by $200 charge warning (if the fault is inside my house). Anyway agreed for a technician to check. Everytime they did something on their exchange to boost the connection, despite that I personally asked them to check the cables. Helped for a while but than again. Got sick of such service and went to the roof of the first townhouse in the row myself, found the fault just where cables were about to go to the wall (old rusty clip-like connection), cut it and soldered the cables. Problem was solved at last! Their contractors were not so keen to check the cables, at least visually. They always wanted to go inside the house or concentrated on the exchange.
BTW I like Slingshot in whole. Used to have 3 different broadband providers before them.