New road bike: alloy dual pivot brakes work poorly
In the USA at least you can take a bike back to the store you bought it from and ask for problems to be addressed. However I googled 'Giordano Acciao' and I'm guessing you got this bike from Amazon or a department store, so that's likely not an option for you.

no offense meant, but bikes from Amazon, Walmart or department stores are the lowest quality and can be barely be usable. The performance you are getting may just be the best the low quality components can provide. 

That said there are a number of things you can try to improve things. Check the pad alignment and brake adjustment. Park Tool has a good video showing how to do that here. The pads may need a little wearing in and will improve as the outer surface wears off and the pad conforms to the rim. You can also buy higher quality pads from a dedicated bike shop.