Battery drain in 2days

It may be the dealer changed the wrong battery. To check the batteries and other battery drain issues here is how: With both batteries fully charged simply disconect the + on the older battery when you have stopped for the night. Then In the morning check the voltage in both batterie's. If the older battery is still fully charged then it is O.K. if it has lost charge then most likely the new battery is leaking power through the older one when the power goes down in it. If it is now confirmed the older battery is good then check the voltage in the new battery it should be low. The most likely reason is a faulty alternator although it is charging the batteries when the car is running it may be draining it when the car is stopped so this is the next check. Connect the + on the older battery again. The next night after stopping for the night and with the batteries fully charged again disconnect the wires on the alternator in the morning check the voltage in the batteries again.If the batteries are still fully charged in the morning then its alternator trouble.These checks you can carry out yourself so won't cost anything Replace which ever (if any) is faulty. When you have performed these test's and the problem. These are the most likely causes but their are a few other check we can perform if the problem is'nt solved .Get back to me after you have done the above check's and if you still have the problem I will advise further.

I would have changed both the batteries the first time. Little expensive but usually if one battery is shot the other one isn't far behind. I ran into this problem before only on a my ford , I managed to track down the problem after several days of checking wiring harnesses ect. turned out to be the positive cable lead between both the batteries.
I would have a scan done, money well spent at least you won't be pulling your hair out and playing the guessing game. Some places do scans for free, phone around and find out.

Well there either something staying on and draining the batteries or your alternator isnt charging the batteries.