A3 fuel gauge off-set

Hi,
my low-fuel alarm came on yesterday but the gauge still said there was over a quarter of a tank left. Went to fill up anyway and found that the tank was almost empty. After filling, the gauge needle was fully deflected to the right and off the scale so it looks like the needle is off-set now for some reason. Anyone come across this before or know is there an easy way of fixing it? Electrics are fine in the car, had to change a bulb at the weekend but that hardly had anything to do with it...or did it?!
Thanks.

Old man used to have a CLK and had the same problem. The problem was actually with the detector in the tank and not with the gauge. It was a simple and non expensive repair as far as i can remember.