Camping World new batteries gone dry Avondale Arizona

Bought 2 new batteries for my RV 6 months ago, 4 months later i noticed the batteries were not holding a charge very good, 2 months later I had them checked at an auto store, they said they were not holding a charge . Took them back to Camping World and they said they can not warranty them because they had gone dry and one had regular water in it . These batteries are each over 100 dollars and 6 months old and strored in my RV in Flagstaff AZ where temps do not reach over 90 degrees ,  the salesperson said they could have dried out because of the heat. REALY