That's not how things work unfortunately.
The marketplace is open and publicly accessible. So are the threads, and the reviews from users.
If you have a query, you're welcome to ask them in public. As this is a large marketplace, you finding a particular member who has experience with all the sellers is impossible. People are usually honest with reviews. You can and should also check the dispute section for any active disputes. Along with the seller's post history as well. Lastly, when transacting - ensure you steer clear off of any apps where chat history can be deleted like telegram.
If you'd like to have a text chat, you can use Telegram to explain your requirements to the seller.
Then ask them to message you on BHW forums with everything they will be providing (a gist of your discussion), the ETA, refund terms and their payment details (PayPal, Crypto, Payoneer, Stripe etc.)
Agree to the above, then make the payment and post confirmation in the same DM. Ask the seller to confirm the payment there too.
This will make it easier for BHW moderation to verify what was promised, the payment itself and the agreed upon terms and ETA.