R13k bill for ´water damaged´ MacBook Air

So I have this Macbook Air mid 2013 which worked fine until one afternoon when it just refused to switch on. I took it to Hatfield iStore and long story they eventualy asked me for R13k to replace he laptop alleging water damage. Problem is the laptop did not come into contact with any liquids and since I live alone I know that for a fact. Second problem is in 2015 the laptop had another logic board problem which Apple fixed for free because it was a known issue for that specific batch. Considering that I am absolutely certain I did not spill any liquid on the laptop (dont know if moisture from an adjacent bathroom can count) and this laptop has similar problems before what is my course of action? Does anyone with a similar model ever faced the same problem? Assuming they are right, how is it possible that a laptop gets water damaged without me knowing it, arent there supposed to be some telltale / warning signs before the laptop kicks the bucket?

Water damaged is the classic "we don't know what is wrong with it but we have to bill for all the time we spent working on it" trick that comes from the cellphone repair industry

Motherboard / Logic board failures will often just happen.
Insurance? Use the repair quote to justify the replacement...

TFTC said:

arent there supposed to be some telltale / warning signs before the laptop kicks the bucket?

Click to expand...

No... none at all.