Other Fuel System Tank Assembly problems of the 2016 Mitsubishi Outlander

Drive 2016 Mitsubishi Outlander sport. Oct 2018 started experiencing problems with the fuel gauge sender behaving erratically. Fill with gas and may show full tank or 3/4 tank, within less than mile the miles untll next fill will jump up. While driving it will jump all over the place - in less than block it went from 390 to 440. Has been as high as 460. The last time I took it in I went over 300 miles with the fuel gauge showing 3/4 full. Has a 16 gallon tank so on 4 gallons I would have averaged about 75 miles to the gallon. Have included chart of one fill up showing the mileage and what the fuel gauge shows for miles to next fill. Have also included some pictures to show differences. Some instances I park the car and it will show the miles to fill and when I start it again that will have risen by 10's or dropped by 10's. Drive 7 miles one way to work and it has given as many are 6 different readings during the drive. Has been one year and still no fix and am afraid of what will happen next. This happens at all different times - driving on highway, city streets, turning, straight. No consistency, just happens. Have taken it to the dealer several times - they kept it twice for a week each time - and they say there is nothing wrong. Also called Mitsubishi and they say dealer contacted them and there is nothing wrong with the vehicle. At wits end on what to do with it. Any help??? vehicle had just over 20,000 miles when began - currently have just over 24,000. Thank you.