I'm also trying to find out my US reservation number and having all sorts of problems. The dining reservation line has been having trouble with a lot of people right now trying to make their ADR's. They can't find UK reservation numbers, and say they can't get hold of the US number you need to ring.
Some have been fine with just their dates and names so hoping it's just a glitch that will be sorted before I have to make mine in just over a month!
I still haven't received my, and my mum's, birth certificates so I can send them back to the passport office. I'll have to get on to them and see what's going on. I should have had them by now.