U-Haul Moving & Storage

Need to move stuff? Rent a truck? Go to U-​Haul, it’s convenient, prices are ok, and the tank gas is acting funny.
I have used the U-​Haul services twice and noticed the same behavior, i.e. gas tank and sensor acting funny. Once you have finished using the vehicle, you will have to return the vehicle with the same amount of gas at the time that it was given to you (in my case half tank). We go and start putting some gas (5 gallons) into the vehicle the gas sensor does NOT move at all! We go for a ride to see if this make the sensor change… it does change a bit but still missing ¼ of tank… go for another gas station to «fill» it to half tank… sensor does not move again… we go for another ride… and suddenly the vehicle has MORE than half tank!
How do you explain this at all? The gas tank and sensor are acting funny… Yes, you as a customer need the car for moving or you simply need the space to transport stuff. But the gas situation it’s just not customer service oriented.