LOL

If the whine disappears when the tank is full of fuel only to come back later when you have used some then its the lift pump inside the
fuel tank that has died. The whine is the main pump overloading or air bleeding through becasue the lift pump is not supplying fuel to it.
The lift pump is easy to change, through the blanking plate in the bottom of the boot. I would recommend a VAG one. I got one from GSF but it is quite noisy and does not fit the OE strainer.
VAG: 191 906 092 AD £24.03 I think but get the dealer to confirm part # first.
Edit: replaced fuel pump with
fuel tank doh!