Sorry you are having problems with your Aquos. Mine died (32" jobbie) and Sharp's customer support was dreadful. Luckily I got mine from Comet and their support was spot on - after a couple of week of them trying to get Sharp to resolve the problem they took the set back (it was within warranty) and replaced it with a Sony.
All I can suggest is that you get on to Sharp and make it clear that you expect decent support.
Push and keep pushing - they do seem to have a known problem with this switching system. Its similar to What happened to me and I found quite a few references to the same problem, mainly in the States. Maybe worth doing a Google search before you contact them?