Did you get your missing pieces after? I recently bought a Marvel Super Heroes set and had two lots of Wolverine's legs and missing Deadpool's legs. I did the online form for missing pieces and had the same response as you. I couldn't find my instructions anywhere (I suspect my mum might have binned them by mistake during cleaning. That will teach me for leaving them lying around downstairs) so I looked online and found the online structions like the ones linked here and sent that code off. That was over a week ago and I haven't heard anything back :(