Got a call this morning from the SA, who said they ran the diagnostic overnight and determined that the cause was "the parking lights were left on"

What a load of BS.

My dad completely lost it on the phone this morning and is going to speak with the manager, as he repeated that he did not do anything as such, and I don't think he would. More than likely a fault with the system- any help on this?

We're not going to pay $600 for a new battery. If this means hiring a lawyer, so be it.