All OEM companies, and most 'repair' places like BestBuy all have a standard:
When the computer was taken out of the box, it was working AS advertised, so the solution to ANY problems is to put it "back to factory fresh" which will 'always' work.
This of course totally disregards the customer's data, setup, etc. but fulfills the only thing they care about - removing liability.
In regards to your laptop charging port, it isn't a simple ' swap a 10Cent part out' and hand it back. The parts inside your laptop are all FUSED together, onto the Motherboard. To 'typically fix' your problem they would had to complete disassemble the entire computer, every part completely, then order the EXACT same motherboard - USED. See they don't sell 'motherboard parts' like you can buy things off the shelf in Walmart. Then once they replaced it it immediately wouldn't allow Windows to run (you replaced the motherboard which violates the license), so they did the 'reduce liability' and used the Factory CDs to 'make it like out of the box' and it worked.
Not the best answer, but they did do exactly as they promised. They fixed and handed back your laptop working AS it was when you first unboxed it. So no legally and technically they didn't 'cheat' you.