I would give them 10 days from your first refund request and then dispute. This indicates that you were proactive in attempting to solve with the vendor and you will have the charge removed while CO dilly-dallies.

IME, CO refund department never actually does anything until you have called multiple times. When you finally get an agent to react to it, they will profess surprise at the fact that nothing happened. ("Gee, I wonder why this hasn't gone through yet. Let me check. Please hold.")

I recently had an upgrade fee double charged and the upgrade did not clear. It took almost 8 weeks to get the refund and that was after an email, a fax and 5 phone calls. To their credit, when I finally got someone to act, it only took two days for the credit to post to my account.

CO service at its best!