To have your payment method changed you should first ensure that your account profile has been updated. Then simply open a support ticket with the category "Billing Issues" stating you'd like to switch your payment method and which method you would like to use.
**When switching to credit cards**
The sales team will reply to your ticket once they have updated the billing method. Then you must add your credit card number to your profile and ensure that you have the correct profile information that matches the credit card. Once you have completed this, reply to the ticket saying that you've finished updating the CC and info.
ONLY TYPE YOUR CREDIT CARD INFORMATION IN THE PROPER CREDIT CARD LOCATION!!!