I helped an inlaw with their car years ago.
the battery was flat, got it started, tested and alternator was duff.
took it off and told her to get her husband to get a replacement tomorrow and where to go to get it and I would refit it.
wanted me to do the running round I was busy ffs.
Fits part and car is fine.
about 14 months later I get a phone call out of the blue which starts.
"That part is crap etc"
When I finally realise what the rant is about I explain the part is over 12 month old etc and there could be another reason causing the alternator to fail.
suddenly its my fault she can't get to where she is going so I suggest a taxi and I shall look at the car when I get chance.
turned out the interior light had been left on
So I removed the battery and put it on charge and explained how to take it off charge the next day etc.
I got my battery charger back blown
The next time I gave her the phone number for a local garage I know