Step 1: Respond to them in a friendly tone and see if you can resolve it. Reach out to the person.
Step 2: If after 1 month, you can't connect with them, edit your response to include the steps you took and a detailed description (without revealing personal details) the issue, how you tried to resolve it.
The 2nd step is important that you keep a friendly tone and show to other people looking at your reviews, you tried to remedy it. Remember the user can also edit their review, so don't try to lie - it can get easily called out and become messier.