How can you stop a purchase and still download

Hey Noodle_lfc,

Thanks for the question. If you have an unpaid balance or purchase, you'll need to take care of the debt before you can purchase again. The following resource outlines how to take care of an unpaid balance:

Why can’t I select None when I edit my payment information?

http://support.apple.com/kb/TS5366

Using an existing iTunes Store or App Store account

If you have an unpaid balance or payment due, you can't select None as your payment type. To see which order you need to pay for, view your purchase history. When you sign in to the store, you may see a message that there was a billing issue with your last order. Click the Billing Info button to see the order.

After you pay for the order, you can change your payment information to None.

Additional Information:

iTunes Store: My credit card's security code or zip code does not match my bank's records

http://support.apple.com/kb/TS1646

iTunes Store & Mac App Store: About payment card authorization holds

http://support.apple.com/kb/HT3702

Thanks,

Matt M.