Fuel Gauge and range

Hi all. I have recently had a problem with the fuel gauge and range on my scenic 2 57 plate. It is giving me erratic readings. When I put in £20 of diesel from I assume reserve. I get 4 levels and a range of 280 miles .... i do about 3 miles and turn off the engine. Next day i would get just the reserve light and the beep and nothing on the range..... park up again i i would get a random 1-4 levels back on the fuel gauge. and the appropriate range. Could the fuel sender be faulty and replace ? I have done the reset switch on the wiper stick and everything resets. apart from the fuel gauge. I have disconnected the battery hoping the ecu would reset but this hasn't worked either.

Thanks.

Fuel Gauge and range