I know how frustrating this must be for you... but I think all you can do is sit tight and wait for them to contact you. If the entire computer system was down then there will be thousands of missing and misplaced bags, and the fact that you can't get hold of them by phone probably just means that everybody else is trying to get hold of them too.

If the bag hasn't even been traced you are not going to achieve anything by phoning them - all they'll be able to tell you is "sorry, we haven't traced it yet, but we are looking" (which you already know). Best thing is to let them get on with sorting all the backlog, and just check the web site from time to time to see if there has been an update. Everything else would be a waste of time and energy.