Yet is used to talk about something that is expected to happen. Still is used to to describe something that is still in progress or isn't finished yet.

Sono simili però da quello che so io si usa still soprattutto quando continui a fare una cosa tipo: I'm still smocking cigars. Mentre yet lo userei piú per una cosa che ancora non sei riuscito a fare,anche perché andando a fine frase da propio l'idea di ancor non compiuto: I didn't reach my house yet. Poi per le domande é da preferire yet: has it stopped raining yet? Per la risposta o usi it hasn't stopped raining yet oppure la forma con still. Bye

Try sending a message to the help people, maybe they can fix the problem.

Yet ‘Yet’ is used to talk about something which is expected to happen. It means ‘at any time up to now’. It is used in questions and negatives. Have you finished your homework yet? The speaker expects that the homework will be finished. I haven’t finished it yet. I’ll do it after dinner. ‘Yet’ usually comes at the end of the sentence. Still ‘Still’ is used to talk about something that hasn’t finished – especially when we expected it to finish earlier. I’ve been waiting for over an hour and the bus still hasn’t come. You promised to give me that report yesterday and you still haven’t finished it. ‘Still’ usually comes in ‘mid-position’ Still is often used with other tenses as well as the present perfect. I’ve still got all those letters you sent me. Are you still working in the bookshop? you can find more here http://learnenglish.britishcouncil.org/ar/grammar-reference/just-yet-still-already