Complaint about delivery of the wrong grade of copper.

Immortality by any means.

The British Museum has a 3700+ year old clay tablet that is the world's oldest complaint letter. Found in the ruins of Ur, in 1953, it has survived intact and relates a complaint from Nanni to Ea-nasir about inferior copper. Ea-nasir will live forever as a cheat and a bad businessman. References around the Internet tell that Ea-nasir had a room with multiple such complaints, although I was unable to find credible confirmation of other tablets.

The text of the tablet is as follows:

    Tell Ea-nasir: Nanni sends the following message: 
When you came, you said to me as follows : "I will give Gimil-Sin (when he comes) fine quality copper ingots." You left then but you did not do what you promised me. You put ingots which were not good before my messenger (Sit-Sin) and said: "If you want to take them, take them; if you do not want to take them, go away!" 
    What do you take me for, that you treat somebody like me with such contempt? I have sent as messengers gentlemen like ourselves to collect the bag with my money (deposited with you) but you have treated me with contempt by sending them back to me empty-handed several times, and that through enemy territory. Is there anyone among the merchants who trade with Telmun who has treated me in this way? You alone treat my messenger with contempt! On account of that one (trifling) mina of silver which I owe(?) you, you feel free to speak in such a way, while I have given to the palace on your behalf 1,080 pounds of copper, and umi-abum has likewise given 1,080 pounds of copper, apart from what we both have had written on a sealed tablet to be kept in the temple of Samas. 
    How have you treated me for that copper? You have withheld my money bag from me in enemy territory; it is now up to you to restore (my money) to me in full. 
    Take cognizance that (from now on) I will not accept here any copper from you that is not of fine quality. I shall (from now on) select and take the ingots individually in my own yard, and I shall exercise against you my right of rejection because you have treated me with contempt.
-Letters from Mesopotamia : Official, Business and Private Letters on Clay Tablets from Two Millennia " by A. Leo Oppenheim. p82-3

I find it interesting that most history books only deal with big events: wars and battles; coronations and despoilments; floods and famine. Real history can be just as much about the tiny details as the great ones. This complaint letter would not be out of place on the product comments on Amazon, or in the letters to the editor in a newspaper. Historians tend to lose sight of the fact that people in antiquity were just as much human as ourselves: not statistics but living, breathing people with hopes, desires and the will to complain about the same crap that we do, today.