Simon Says allows you to use one credit card for subscription payments and a different card for transactions.
To change your credit card used for transactions:
Upload media you would like transcribed
Click the "Transcribe" button
Untick the "Use The Card On File" option
Enter the new card details
Tick "Update Saved Card" if you intend to use this card for future transactions
Click "Let's do this"
Your new credit card details will now be used.
To change the credit card used for subscription payments:
Click My Profile at the top right of your page
Click Update Payment Details
Enter your new details and click Update Card. Your card will be updated and saved for all future payments.
Related Help Articles:
About Simon Says
Can I purchase in advance and prepay for transcription / translation credit?
Can you handle translations?
How do I upgrade or downgrade my account?
How much does it cost?
I haven't received my email confirmation
What payment methods do you support?