I was so upset with the fuel guage - it is utterly useless and in my reckoning - a compulsive liar. Solution - brim tanks (spill at least 1-2 litres all over forecourt in process)- reset trip and drive a maximum of 250 miles. Then refill. I got to 287 once and ran out so I keep a 5 litre can under the bonnet for emergencies - fits well with a bungy and some Velcro.
All is sweet now I ignore it.