Tail Light Switch problems of the 2012 Mazda CX9

Both my tail lights form condensation. I contacted both the dealer and the corporation several times. The corporation maintains this is a normal occurrence that comes and goes depending on the weather conditions. Consequently they don't consider this a warranty issue, as a result they won't do anything to remedy the problem. The service manager from the dealership informed me that they use to replace the faulty unit until Mazda refused to reimburse them. Their excuse seems to be absurd considering the unit should be sealed.