There is not much we players can do about it indeed.
The only things I can think of are:
did you perhaps sell the characters back then and forget that you sold them? If so, I think you should be able to find back the post of the sale on the forums, as I do believe the character being sold needs to make a post.
did you perhaps have multiple accounts and accidentally expected to see the characters on the wrong account? For example, what if you had characters on account 1 and 3, yet now you paid for account 1 and 2 and are missing the characters on account 2 (that were in fact on account 3).