Bora Fuel gauge reading full on empty tank

[cubby]

Hi I wonder if anyone can help, today I got into my X plate bora tdi, starterd it up and the fuel gauge went to full.

I know that the tank was empty from the night before, so unless the fuel fairy tanked it up in the middle of the night could anyone shed some light?
:confused:
P.S. today was very hot if that had anything to do with it. Cheers