As written in many postings below, the windows store problem that occurs with some apps (my app Week View is one of them) still exists. The app cannot be updated for some users and when trying to do so, a windows phone store error is shown.
Today I got another email from MS support member „Mary“.
(click on the image to view it in full size)
In short: The problem still persists. Since it’s a windows store problem there is nothing I, as a developer, can do about it.