These are OUR IT person's responses when I questioned the repairs.
"The airport card is connected to the motherboard, and one of the spots was on the actual airport card and the others on the motherboard so both where changed and replaced. Note the airport card is always changed when the mother board is as they are all one welded part."
"The top case and keyboard are one unit and they where replaced because of the water damage on the keyboard and keyboard casing which is connected to the motherboard. They had to change all parts of the computer where there was water damage or water marks. They do this as their is oxidization created from water, and can lead to problems later. This is a standard procedure."
Is this true?
The first paragraph appears to not be true (upon first reading). Unless a certified tech can correct me, Airport Cards are a
separately ordered part and plug into the motherboard.
However, if evidence of liquid spills have been found on BOTH the AirPort Card AND the Mother Board, then these would both require replacement.
Without having access to the MacBook to to troubleshoot your charger problem, it is difficult to say whether the liquid spills were the real cause of the charger problem OR whether the "tech" opened the machine, saw evidence of corrosion and said "We'd better replace these parts because I see corrosion on them".
Jumping to the conclusion that "They broke it and are now expecting you to pay" is pretty unjustifiable. That said, replacing a motherboard and Airport card and top case simply because "I saw evidence of a liquid spill", is equally stupid.
But, to add to that, I am aware that Apple Certified Techs and workshops are NOT permitted to do anything to faulty circuit boards. In this situation if it's just "spots" and I was conducting my own repair, I'd be cleaning the affected area, re-checking for corrosion, desoldering components and rechecking the area with a 20x lens.
Liquid spills on laptops are a real pain. If an affected metal part (motherboard, shielding etc) is not reworked or replaced, it can grow into a bigger problem later, much the same way as rust "grows" on a car. You either cut the rust out and add new material or you replace the affected panel completely.
I would ask, if you are permitted, to post the pictures they sent. On another note, obviously they are not repairing your old MacBook, but have assessed how much value (in terms of spare parts) have been lost. If I understand the situation correctly, they are now only expecting you to bear half that lost value. Apple logic boards and case parts are often this expensive.
Hope that helps...

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Toyota P transmission