To check if quality quantity and price are correct the consumer is always the controller in the end! Although producers and hallmark institutes do their continuing checks they can only check at random. Which means per definition that only 98 % is ok. In calculating those plus 2 percent in the prices these last 2 percent are already financed. That means that every discussion about guarantee should never be about the failure of the product itself, but only an understandable investigation if it occurred because of mistreatment by the user himself / herself.
In practical daily life all kinds of situations are of course much more complex. Mistakes, badly read or written instructions, irritations, transport and insurance, etc etc. So therefore often actions have to be taken to solve the dispute. (for instance: 1. Go to another retailer first for a "second consult" so you can see the problem in the best perspective 2. Google to the website of a Consumer Authority or institute where you can find all information about consumer laws 3. Talk with your retailer 4. If problem not yet solved go to consumer organization for individual or collective help 5. Sometimes a problem can generate ideas for new solutions (hallmark organizations are especially interested and willing to help)!