My question involves a condominium located in the State of: NC

Last wednesday during the night sometime my upstairs neighbors hot water heater bladder busted a line which ran for hours. I awoke to the sound of running water in my unit. the upstairs unit is vacant as the owner is trying to sell it. my unit has suffered tremendous damages. sheetrock, ceilings and flooring will need to be replaced in 90% of the unit. I had water pouring out of the AC vents, light fixtures, and fire alarms in just about every room. the upstairs unit's insurance stated they will not pay because the unit owner wasn't negligible because he didn't do anything wrong. the bladder on the hot water heater was installed improperly and eventually fell over breaking the line. I need some advice as to how best handle this. My insurance company is stepping in with my policy but i fear my covered may not be enough. also, the HOA is not stepping over to cover common areas. They stated that they would have dried my unit out. there is no possible way that they could have dried out the gallons of water that were trapped between my celling and the upstairs floors. i was wondering do i have any legal recourse to engage either the upstairs units insurance of the HOA's. According to the upstairs units insurance he has to be negligent. Isn't leaving your electricity and water on when not living in a home negligent?

any advice would be greatly appreciated.