It's almost impossible for a Sr member doesn't know how to check their own UID account. I mean, you have spend more than 8 months to achieve that rank but you don't know simple thing like this
Sorry for a bit off topic
Why would it seem impossible? I really don't see any reason why a casual user needs to know how to obtain their user id. Furthermore, the OP mainly has posted in the Turkish board. So it may justify his confusion with Yobit's instructions. From what I can see, the user is now posting in English. I recommend that the OP sticks to posting in the Turkish boards or he won't be welcome in Yobit's signature campaign for very long.

Is there any possibility that somebody rented/loaned the account so that they can make some BTC from yobit campaign.
Your explanation makes sense as there is no campaign in local boards so guy never find out.
But still, it is a quite easy to find and someone having rank of Sr. Member is not able to find it raises doubts.