I have a 2011 XF 2.2 190. A few weeks back,I noticed all the windows down (global opening) whilst the car was parked outside my house. The fob was on the kitchen table. A week or so later,I get a SMART KEY BATTERY LOW warning on the dash. I change the battery,twice,and now the fob isn't working. Car has done very few miles recently, I'm hoping that a good run with amend things. Smart key still works when plugged in. Anybody any similar experiences?