Whether you are directly hired by the company as an employee or are outsourced makes no difference. Neither does it make a difference if there is another link in the chain. You are the public face of the company, and represent them. Maybe, as an outside agency, you are doing this for multiple companies at once. Great, good for you. Perhaps your management have also not realised that part of their role when hired in this capacity is to represent the companies that hire them.

Maybe you find it better put like this: The company you are contracted for will start to get a bad reputation for customer service, more direct complaints, lose sales etc. A company that DOES realise this and provides good customer care will eventually start taking away your contracts and you will end up with no job. You will be left saying "consumers are asses" because they want things to work. Good luck with that. Maybe instead you will be blaming the original manufacturer. I can only suggest trying their customer service number.

As I said, I rarely get angry with customer support people because I am not stupid and recognise that they are reading scripts and have limited power blah blah blah and because I'm going to be treated better by being nice even in the face of rampant incompetence. The fact of the matter is that most customer support companies do not actually provide the best solution for the situation given in any but the most trivial cases. That may well be an organisational problem (maybe the fact that all supervisors seem to be permanently on holiday has something to do with it?) rather than the fault of individual employees on the phones, but I can only suggest you try to see it from the customer's point of view as you ask them of you.

That may be what happens, but it doesn't make it right. They are representatives of the company whether their IQ is high enough to recognise that their job entails that or not. If the company is supplying a faulty product/service and won't deal with it properly, they are being a dick to me. There comes a point where being nice back to them still isn't getting things done, so why not match their attitude to at least try to get someone's attention?

Personally, I only go down this route in extreme cases (say 12-18 months without getting what I'm owed in two recent examples, or being taken to court for utility bills incurred for somewhere I don't live). Being nice in all the other cases seems only to turn them into examples like this. Only once has it resulted in something actually getting done (Amazon (.co.uk), by the way; exemplary compared to the rest of the industry).