TELLERS AT POLLING STATIONS
On election day volunteers for candidates called tellers wait outside polling stations and ask voters for the number on their polling card. They use this information to check who's voted so they can remind those who haven't to do so.
They are not acting in any official capacity so you don't need to give them any information if you don't want to.
If you are concerned about the conduct of a teller, speak to the presiding officer at the polling station.