missed gear change problem

G'day all, I have a MK1 206TSI R-Line and it has a strange little problem that our local VW dealer has been unable to identify. In the last couple of weeks the car seems to miss the change from D1-D2 at lowish revs on flat even roadway. I get a "ACC not available" message on the dashboard. The transmission seems to sit in neutral for a second or two before engaging D2. Has anyone else had this issue? and more importantly have VW fixed it?