If the buyer has not contacted in accordance with the rules of the site, you need to invitethe moderator to the chat.
Go to the Sell/Sold section of your account and click on the chat icon.
In the opened chat there is a list of sold or bought lots. Near each lot there is a button in the form of an ellipsis. Click on the button, in the menu that opens, select the "Invite moderator" item.

In the window that appears, click "Yes".
Be sure to briefly describe the reason why you invited the moderator to the chat, and click "Submit".

From the moment the moderator is invited to the chat, the lot from the list will be highlighted in blue. Expect a moderator to reply in the chat soon.

If the buyer does not contact in accordance with the site rules, you need to invite a moderator to the chat.
Go to the Sell/Sold section of your account and click on the chat icon.
In an open chat, click on the "hammer" icon and a list of Sold lots will open

In the lot menu, click on "..." lot menu, select "Invite moderator"

Be sure to briefly describe the reason why you invited the moderator to the chat and click “Submit.”

From the moment the moderator invites you to the chat, the lot from the list will be highlighted in blue. Expect a moderator to respond in the chat shortly.