The fallacy is that "we've heard this complaint before therefore your complaint is invalid" which is obviously an invalid argument. In this case "moderate level

The fallacy is that "we've heard this complaint before therefore your complaint is invalid" which is obviously an invalid argument. In this case "moderate levels of people complaining" is treated as negative evidence, that is to say, counter to their complaints. My vote for the name of this fallacy is "the boy who cried wolf" fallacy.