unsatisfied service

On February2015 I bought A3 Samsung, which the phone was working very well till June 2015,the problem about this phone is when charge the phone it doesn't charge more than 3 %,, it's forever lower,I took the phone to service providers and they told me they have to book it for repair which it will take 21 days, I couldn't wait for a few days without my phone.they advice me to go to Samsung smart centre for repair if I can't wait for 21 days,I took it to Samsung repair, I explained what it wrong with my phone (my battery is forever lower) they told me that my phone needs to updated software only then it will go back to normal and their is nothing with my battery, then they update my phone, I ask them if still going to give problems no everything work normal, when I get home started to charge my phone, it's still the some no improvement, my problem is my phone it is still new and it's giving problem already, A3 Samsung don't came with the battery, I travel 75 km for nothing and I am using my own petrol, I am using my phone for business too, and I don't have time to run around for the new phone, if it was old phone I was going to understand but new phone, Samsung please help