CMK10 has raised a very good question – is there a missing mileage amount that is too small to dispute? Naturally opinions differ widely, so I guess it literally is a case of YMMV (your mileage may vary).
It sounds absurd, and no it isn’t April 1, but one frequent flyer program has introduced a fee to claim missing mileage. Yes that is right. If the airline fails to credit mileage then a fee is applied to get it fixed. Read about it, and the reactions, in LAN’s 1000km fine for missing mileage.