Won’t start AGAIN!

Gave the car to my wife for her birthday just before Christmas, drove it for 4 days, since the dealer agreed to store the car over the winter we let them store it. 2 weeks ago we picked the car up from the dealers. Drove it about 250 km the first night, left it in the garage for 2 days went to start it and it would not turn over at all. Put the charger on it, next morning it started and took it to the dealer. Dealer kept it over night to fully charge the battery and to test the electrical system all seemed fine. Since the weather was poor (raining and cold – just above freezing) did not drive it for 3 days, again would not start (it would not even allow me to turn the key). Put it on the charger and drove back to the dealer, again they kept it for 4 days, put a new battery in and they tested it by starting it every morning without any problems. Picked it up last Friday drove the car for 50 km on Sunday, went to start it tonight – 4 days later since it was a beautiful night 68f and finally sunny, but it might as well been raining as IT WOULD NOT START AGAIN. Tonight I sent a couple hours reading some forums and have found some others have had this problem and I think it might be something that I’m doing.

Since I always leave the cars in the garage I always leave the keys in the ignition, We have a Lexus and a Chevy, this has never been a problem with them, but now I’m wondering if this is the source of the problem? Any feedback would be appreciated as I have a CTEK charger on it now and I’m back once again to the dealer.