Hi Geraldine,

Sounds like an issue with the sender unit in the fuel tank. If the car is still under warranty, bring it back to the dealer and they should get it sorted for you. If not, bring the car to a good mechanic to fix it. It should not be very expensive to do. Might be worth mentioning to them that that car is known to throw up all kinds of odd electrical issues because of a loose connection between the fuse board the wiring loom, too.