You could always call your credit card provider to change you CC # and never use the new one to pay your Sprint bill.
I am a Sprint Customer and without asking Sprint has stored my credit card number in their system. (In the past, I have used the credit card and done a one time transaction and this was not a problem.) The customer service rep said there was no way to delete my credit card number from their system. I have asked to speak to a supervisor and am still in process of getting an answer. My question is simple: "What can I do to get my credit card number taken off their system?"