Previous owner had my car parked and abandoned for over 3 year. In order to buy it, he had to replace the fuel pump with a brand new, genuine. I am sure about that. But, the mechanic did not connect in the right order all the wiring and tubes and when I had my tank full the indicator was going only at the 1/2 position. When I had in in my possession I went to another mechanic in order to fix it. He had to reopen the tank and reconnect the fuel pump. Since then, I filled it and the indicator went almost between the 3/4 and 1. The mechanic told me that as I continue to use the car the air will go out. After 4 months I wanted to make a big trip so I had it full. Again the same thing. Second stop for refueling, same thing.
Is there anything I can do or have to visit the official service?