Hi
This is a known fault to BMW and they should recall on the issue. When the fuel sensor fails it allows fuel to leak and create havoc/damage, so yes we agree.
We were quoted £4000, we complained to BMW and were offered half, we still felt that we should have been advised and given the opportunity to replace the sensor at £150, so ended up paying £1500, reluctantly! Stick to your guns, they know this is a design fault, shameful.
We bought a BMW for its safety record and reliability, such a disappointment when this sort of thing happens and shows utter disrespect to loyal owners.
Good luck!