My toilet tries to top up water constantly when not being used.

Can you give advice please

More details please! Apartment or single family dwelling? Are there any units above you? Let me know, Tom

Sounds like a leaking flapper. Put some food color in the tank and look in the bowl in 5 minutes. See color in the bowl?

Brain,
Did I misread the complaint?
My toilet tries to top up water constantly when not being
His complaint was that his bowl filled up to the top WITHOUT any use. Not that it was leaking from the flapper and refilling. Sounded to me like he had a partial blockage and a upstairs neighbor flushing down on him. Let's see what he has to say. Regards, Tom

I am with you Tom, somebody is filling up a clogged drain from above.

Guess we'll wait to hear from them!