First of all, A spyware went into your computer, Its a type of Malware which is able to detect every single move on your computer. When you were vulnerable (using your credit card) It was able to steal its info and directly send it to the spyware creator.
And btw, McAfee is one of the best Anti-Virus so far, if it wasn't, then It wouldn't be a part of Intel now.
How do you know that was the type of malware which his computer has/had? Also, I believe AVG is one of the better ones and I've also heard about Avast. I used Mcafee in the past but maybe it's better now since it's owned by Intel.