re-fuelling problem

g'day les and group,
as you eventually know, we're just having our gearbox repaired.
we want to take the opportunity to have the "re-fuelling problem" solved (when filling up the tank, the pump stops, altough there's room for at least another 10 litres of fuel).
we know, you were working on a solution...any help greatly appreciated.
thank you in advance
joachim and jasmin