I expected this refund to process immediately but the constituent says they have not yet received the refund.
The time that it takes for a refund to show up on the credit card statement usually depends on the card issuing bank. It is usually with-in 24 hours on a normal business day but I have seen it take 14 days sometimes. To check if there was a transaction adjustment you should look at the interactions on the constituent's profile. Click both show all buttons and it will give you a full interaction history. One of the interactions should indicate there was a refund and when it was completed.