I upgraded to a Samsung 6 edge with faulty battery

Hi <br> I upgraded from a Samsung s3 to a Samsung S6 edge, I had the phone for exactly a month and it started dying faster, the phone didn't charge properly and the battery just never lasted! <br> Also I have a complaint about Samsung store in vodaworld, they were not helpful at all, and they were very rude and completely uninterested in helping me and looking at the phone to see what the problem was