Advice on how to eliminate spam with xx ru

We have posted vacancies and bots constantly write personal messages such as "how to get a job with you" in telegram to the main account from which the registration was. however, none of the bots answer where they got it from. if you change the nickname in the telegram - it does not help. but if it is completely removed - the spam from bots ends.
You need help to understand where they even pulled him out, because neither in the vacancy, nor in the NN itself can not respond through telegram, all responses go through the site.
Our hypothesis is that there is some kind of plugin in the browser. who parses the phone of the owner of the vacancy and looks for it in the telegram. if there is a nickname - then it makes an auto-substitution and applicants can write there. the NN themselves reply that they have not leaked contacts anywhere and do not know how this happens.
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