Changebacks aren't guaranteed that your bank or credit card issuers will allow it. I've had a bank tell me several times that I can't do a chargeback when there were fraudulent purchases made on my account on the Playstation Network.

Even better, Sony threatened to ban my account and I'd lose all the content I legitimately purchased if I did a chargeback against them.

I buy physical game copies now and I've found CapitalOne is better at doing chargebacks than my credit union is (guess credit unions aren't all they're cracked up to be in certain aspects)