I don't understand the attitude of Hieveryone and the others, who advocate for lying and making a scene. Not because I'm holier than thou and lying is immoral (that's only my personal opinion and I respect that others play differently), but because for the self-serving reasoning that a Genius has LESS REASON to go out of his way to help you, if he catches you lying or if you treat him like crap.
I have previously been given a fresh battery for my 3 year old Macbook Air, 1 week before my extended Apple Care expired, because I was friendly and calmly explained that, yes indeed, I probably caused the battery to blow up by constantly recharging and draining the battery (had some 3000+ cycles), but that I also did that because I made the honest mistake of believing that this was the most sensible way of treating a battery. The battery of my old Sony Vaio laptop from 2005 died after only half a year, because I kept it constantly plugged in and never let the battery drain and I took that to heart and thought I'd be very good with never letting my MBA "overcharge" like this. Little did I know, that this was in fact the worst thing I could have done to its battery. Yet, I explained that calmly, said I was sorry for my stupidity. Of course it helped my argument that from day 1 my MBA never reached the advertised 5 hrs of battery life (2 hrs on a good day), so I didn't have much choice other than to frequently recharge, but still it was my mainly my fault for recharging, draining, recharging, draining... like 5 times a day when the battery eventually blew up.
Before I had elaborated on why I had recharged so often, the Genius was adamant that a battery was consumable and not covered by Apple Care, especially not after 3 years way past 3000 cycles. After I had calmly and friendly explained why I had recharged so often, he very kindly gave me the battery replacement for free.
So don't think honesty is only for weak-ass Green Tea drinking moral people, who get steamrolled in life. It's actually a powerful tool for getting people to like you and help you out when you messed up.
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EDIT: We have a proverb in Austria "Talking gets people on the same side". I always found that I was more successful in pulling others on my side than beating them in an argument, but I know others, who can win any verbal fight and therefor always choose this approach. I suppose in the end, the right strategy depends on the OP's personality: Are you generally more successful in a confrontation where you pressure people to do as you wish, or are you more successful in connecting with people on a friendly level where they end up wanting to help you out?