The link above will take you to a recent newspaper article in the Daily Telegraph. It is titled 'The best passenger letter of complaint'. Is it the best letter? It is quite a good letter with a combination of sarcasm and humour which makes it eye catching. Anyone who has eaten airplane meals will probably sympathise with the complainant but how would you, as a customer service professional, reply?
The link above will take you to a Daily Mail article that tells you how to write a letter of complaint.