@vc commodore, the issue is about a quality sound system install where the end result is hum... Whether hum was preexisting isn’t really relevant as a professional installer would have resolved the issue during the install process. The expectation of any owner who gets such a professional install service is that they can enjoy the improved sound of the new system.
The fact is the new system
now hums with engine rpms. The installer‘s acceptance of this defect is also a fact as the installer took out the newly installed head unit to check their wiring, yet still couldn't fix the defect.
It has no real bearing whether the previous system had hum or not prior to the professional installer getting his hands on the car. He accepted the job and accepted the condition of the system he had to work with... The only real issue is who supplied the head unit and whether the installer can blame the head unit for the hum...
The problem I have is with your terminology that concrete proof is required. In criminal cases, this obligation to prove what is alleged rests on the prosecution, which must prove its case beyond reasonable doubt. In civil cases, it rests on the applicant, who must prove their case on the balance of probabilities. I see concrete proof as behind doubt wiphich isn’t required (but always helpful if you have such)...
In this case the fact the installer tried to fix the issue strongly infers an acceptance of the defect by the installer. Such an acceptance of the defect is rather difficult to counter when the new system hums with rpm... About the only hope is if the installer can reasonably blame the hum on a defective head unit which he may not have supplied... If he did supply the head unit and speakers, then he’s in the dog house.
Put another way, if I go to an installer with a car having no head unit with wiring ripped out due to head unit theft, and pay for install of a new sound system, any hum would be the installers responsibility to fix. Previous condition isn’t relevant as they accepted the condition once they started their task (or when they quoted the job if they inspected the car at that time)...
As is, this case isn’t so much a he said she said as you seem to think... And yes, businesses can be taken to small claims court for anything, even something more resembling a he said she said. and in such cases, if the judge sees the business representative as a slimy eel who can’t lie straight, the judge may find the aggrieved customer to be more believable and thus find in their favour... Sometimes people’s attitude work against themselves and the balance of probabilities can bite people in the butt...
NCAT rulings are probably the easiest accessible rulings of any state and make rather interesting reading for those that are interested in the workings of civil small claims... Often within a ruling the judge makes comment about peoples (applicants, respondent, witnesses, etc) believability and why they rule for or against them on that basis... So where concrete proof may be lacking, other factors can have a bearing on the outcome... but like anything, ones mileage may vary as some other side identical cases and facts seem to end up with different outcomes...
Obviously the first port of call would be the business one is having issues with and in such cases knowledge is always helpful... In this case, knowledge of hum and what causes it and how to resolve it would be helpful and likely lead to a simple solution which can be done on ones own... but this defeated the purpose of getting a professional install... what an irony life can be
