That doesn't sound right, you should definitely try again.
I called LE last week b/c DD2's 1yo backpack ripped along the seam. I got it on super-discount ($10.50 for a $45 backpack) so they would not replace it. But I am mailing it back and they are crediting me for it.
I would definitely expect a backpack to last longer than 2 years, especially at the price LE charges. DD1 has an LLBean backpack that is going on 3 years and still looks new. This year I am trying GH for DD2.