That's how refunds work. Once a credit has been approved by ANYONE, it takes a few days to a week (even longer in some cases) for the charge to reverse. No one can give you your money back instantly. So no, it's not poor customer service. It's how refunds work, regardless of who is issuing it. Additionally, if Apple approved the refund, the credit memo went your card issuer. It's up to them to refund you. If you want to complain to anyone, complain to your credit issuer.
On a final note, this is a user to user only forum, NOT Apple Support. Complaining here to other users is pointless.