Audi A4 won't start

My 2007 Audi A4 2.0T had its battery replaced
about 7 months ago and was working completely
fine. Just recently it had started to take longer to
turn over then began to die on me, I thought it was
a faulty batterie and had it replaced under warranty.
Drove it for a few days and everything seemed to be
fine. I went on vacation and when I came back after
a week it was so dead that I couldn't use my
remote or any of the electronic controls such as
door locks or trunk latch. It was able to boost fine
and drive normal. if I drove it for a decent bit of time
it would be able to hold a charge for a few hours
and would restart but anything longer and it would
just drain out. Not sure where my problem lies since
the batterie is brand new.