In June I started to have an intermittent problem with the LCD display in my speedo so when the car went in for it's service they checked it out and ordered a new speedo. Two months later it arrived and I had it fitted but unfortunately it had not been programmed for my car so didn't work. Last week it arrived back with the dealer and I arranged to take the car in Monday to swap over speedos on starting the car the LCD display worked perfectly and continued to do so all the way there and back!
I think this is called "Sods Law".
They will hold the new one in case mine fails again but as you lose the mileage data I thought it best to retain my old unit whilst it was working.

Worthers +8