Where can I buy toilet cistern/tank screws

So recently my toilet was leaking and after some brief investigation it became clear that it was due to rusty cistern screws.

On the face of it it’s a quick fix right – change the screws- but I can’t find them anywhere!

I bought some on “Fruugo” but today I saw that they won’t be dispatched for another two weeks.

Is there anywhere in Switzerland I can buy those?