How to get a refund?

Attempted to purchase Mountain Lion this morning and install it on a Macbook Air late 2010 model. This won't work at all. I keep getting an error message that the download can't be verified and I should re-download from the Mac App Store. I have done this 6 times and it doesn't make a difference. I tried downloading via wired ethernet, via 802.11n. I verified permissions on my disk (recommended in the support community) and a bunch of other stuff. NO JOY!! I even tried to update my early Mac Pro 2008 model (which is supposed to be supported) and it doesn't work there either.

I am so upset I could spit nails. I WANT MY MONEY BACK!!!! I will now stay on Snow Leopard until and if Apple releases a new OS that isn't Mountain Lion. I think the Lion fell off the mountain and died. Too bad, I used to like Apple. Have to switch to Windows 8 when that comes out. *****, as I preferred Apple.