I would suggest that you contact the Online version of we care. I have recieved two responses in the last two weeks to two different issues and I feel that they addressed these concerns correctly.

In that letter I would mention that you tried to have this issue resolved by the baggage resolution center but that you got the following response (insert response here).

I feel that the WE CARE has been better when I write and usually responds within a 5 to 14 day timeframe depending on what has happened within the system recently (ie IAH Snow/Ice Storm, EWR Snow/Ice Storm, ETC). Good luck!

I should also mention that last year I had a bag that was delivered early and once i got home I found a problem. I reported the problem in person the next day (came in on last flight of the day) and got resolution a month later. I think that as long as you show a reasonable timeframe on your part to report the issue that it can be resolved. If you havent already, I would go to the station where the delayed bag came in and report the missing items to them.