Disappointed in the bike's performance

I had high expectations of the Yamaha Alpha when I bought it three months ago. Unfortunately, I have been disappointed in the bike's performance. The mileage is very poor, only giving approximately 20-25 km per litre. The engine is very loud when travelling at speeds below 40 km/h and the fuel indicator is unreliable, often showing empty even when there is still fuel in the tank. The disc brake is also not very effective. In hindsight, I should have gone for the Honda Activa instead.