By washing your car and giving you a £400 bill i'm doing nothing but forcing a service upon you, which you could do yourself and holds no cost value / saving to you personally. It's an entirely different situation. A better comparison would be, i've found a flaw in your car. Could cost you thousands in repairs if not identified quickly. Could fix it for you if you like for £50. If we agree the terms in writing, i'll let you know what the flaw is and resolve it asap. Obviously this agreement would have to meet certain conditions stated in writing, such that i'd have to prove that it would indeed result in thousands of pounds of repairs if left unrepaired. Fact is, you wish you could identify and fix the problem yourself, unfortunately you're either unable to or don't hold the knowledge to do so.. So a person who does, can.. Which is generally why people goto University, so they can become educated enough to warrant someone else paying them for the knowledge they possess. The world isn't built on charity afterall, especially when it comes to big corporations. Because that's how these sort of situations work. - I inform them of an issue, which will result in tens of thousands pounds worth of lost revenue. - We then come to an agreement in writing that they will pay 'X' if i can prove the validity of my statements - I then prove it - They then pay - I then help them resolve the problem.