There are two sides to the statistics.

On the one hand, 20 percent of the people send in 80 percent of the complaints. That's the old 80-20 rule: the same one that says 20 percent of the people drink 80 percent of the beer, fly 80 percent of the miles, earn 80 percent of the As (or Fs) in school, etc.

On the other hand, 20 percent of the people have 80 percent of the bad luck. That's the same 80-20 rule. If 1 percent of all flights are cancelled, one person out of every million travelers is going to have three flights cancelled in a row. Ditto for lost bags, missed special meals and all the rest. If that person writes in about them, he/she is NOT a serial complainer. It was just his/her week to be dumped on.

Companies generally know this. Someone who complains a lot is either (a) a serial complainer or (b) someone who randomly got more than his/her share of doo-doo.

They have to be able to tell these two apart. That's where the tone of your letter makes so much difference. If you come across as "I'm not blaming you, but I had this series of problems, and here's what I'd like you to do about it," your chances are good. Something along the lines of "I know it happens every so often and this must have been my turn" can help. If you sound like "You did this to me so you are the devil incarnate," it will not help your case.