Hello!
How to do this, when this publication duplicates an advertisement, appears in the user’s message to inform the user that the advertisement has been blocked by the administrator.
And it would be better if the ad was in the panel, user ads, but marked as blocked. Thanks..

Osclass does not have such message function that could be addressed to specific user

For example, "Expired Ads" are shown in the user's personal account.
Also show Spam ads in user account.
Perhaps something to do?

Users are at a loss that their ads are nowhere to be found, begin to write in support

Spam is spam, osclass completely hide spam listings out of front