Just to let the community know that I emailed this to @TriathlonHomes today:
Dear Triathlon Team,
We live in flat […]. The windows of our flat which face the inner yard were just cleaned. I am writing to make clear that the work was not done very well: The terrace door was not cleaned at all (the terrace glass panels were, though), and on the windows, there are still stains which have the size of my palm. Also, the window pane corners were cleaned as it they were round. I tried to take pictures but the camera won’t focus correctly.
Anyway, ll in all not a very good job, obviously done superficially and in great hurry. This was done much better last year, and the year before.