iiNet - best customer service ever
For anyone in Australia (or I think New Zealand and South Africa also) I can't recommend more highly iiNet as your ISP/Phone/Mobile carrier due to the awesome customer service.
24/7 Phone support, no phone trees (or at least so unobtrusive that I can't remember them), genuinely helpful support staff, and even the people on their Sales line have enough Tech savvy to help out with problems.
For those talking about the size of the company being a problem - they are Australia's 3rd (2nd??) biggest ISP and they have offices in NZ and SA for support, hence why they can offer 24/7 support.
Every contact with them ends with an email to rate the customer service you have received from.