Someone in the past day or so started a thread whereby they stated they were charged $25.95 per month by Telstra for dialup internet after a 12-month contract expired and the bill, post contract was now either ~$600 or ~$1200 for that service, some of which is unpaid. The original poster had moved on to some other internet service but was still getting a bill for $25.95 from Telstra each month for the dialup service.
I can't find the original thread but it was poorly titled (had Trujillo in the title but a search of that term failed to reveal the thread) so I will respond here.
My understanding is that these fixed period contracts are an agreement for to a service for that period. The minimum amount payable in the above contract would therefore be $25.95x12 even if terminated sooner by the user.
After the contract periods ends it is typically up to the user to terminate the service and can do so without penalty. The ISP will not typically initiate action to terminate under these circumstanses but will continue to charge a monthly fee until the user terminates the service.
As the poster in this example was getting a bill each month from Telstra for $25.95 he should have acted to terminate that service immediately after the first bill after the contract period. Any debate would have then been over $25.95 and not the much larger sum that is the case now.