Keep getting App store unable to process cc purchases, try again later, when trying to update os X

Question

I'm trying to update my new-to-me MacBook Air from 10.6.7 to Mountain Lion, but the app store won't let me make the purchase. It keeps saying it's having tech issues, but I wonder if I can even use the app store with 10.6.7. And if not, how the heck am I going to get the update? The ultimate goal is to buy & install Pages, but can't do that till I get up to at least 10.7.2
Thanks in advance.

Answer 1

First take the steps recommended in this support article. If there's no change, continue as follows.
Back up all data.
Triple-click anywhere in the line below on this page to select it:
~/Library/Cookies/com.apple.appstore.cookies
Right-click or control-click the line and select
Services ▹ Reveal in Finder (or just Reveal)
from the contextual menu.* A folder should open with an item selected. Quit the application if it's running. Move the selected item to the Trash. Relaunch the application and test.
*If you don't see the contextual menu item, copy the selected text to the Clipboard by pressing the key combination  command-C. In the Finder, select
Go ▹ Go to Folder...
from the menu bar and paste into the box that opens by pressing command-V. You won't see what you pasted because a line break is included. Press return.