According to the
DTG website, engineering work started at Sandy Heath on July 9th (where I'm assuming you recieve from) continuing until August. It states service shutdowns but only refers to Mux B, so that may not be your problem.
If the problem persists, get in touch with a Panasonic service centre as you may need a software update. Over the air updates only happen about once a month if you are lucky. An engineer can plug an upgrade card into the CAM at the back of the TV and fix it in a few minutes.